阅读说明：本技术 一种边坡高层建筑深基坑变形控制的施工方法 (Construction method for deformation control of deep foundation pit of slope high-rise building ) 是由 段玮玮 黄柱 *** 马惠彪 曹露 于 2019-09-29 设计创作，主要内容包括：本发明公开了一种边坡高层建筑深基坑变形控制的施工方法,包括抽水泵、抽水管、固定管、外壳体、电机、导槽一、转盘一、连接槽一、固定轴一、内壳体、外通孔、内通孔、开口、导块二、连接槽二、固定轴二、转盘二、导槽二、连接轴和导块一等；本发明中利用抽条及裙边水泥对深基坑主体基底是在一定范围内搅拌桩进行加固,能有效地对围护结构施工进行控制,减小深基坑围护结构施工对高层建筑影响；本发明中电机能够内壳体上下振动和剪切外通孔与内通孔之间的杂质,从而确保了排液时外通孔和内通孔中的杂质不会堵塞,也就提高了施工的效率保证了施工的进度。(The invention discloses a construction method for controlling deformation of a deep foundation pit of a slope high-rise building, which comprises a water suction pump, a water suction pipe, a fixed pipe, an outer shell, a motor, a first guide groove, a first rotary table, a first connecting groove, a first fixed shaft, an inner shell, an outer through hole, an inner through hole, an opening, a second guide block, a second connecting groove, a second fixed shaft, a second rotary table, a second guide groove, a connecting shaft and a first guide block; according to the invention, the deep foundation pit main body substrate is reinforced by the stripping and skirt cement within a certain range through the stirring piles, so that the construction of the enclosure structure can be effectively controlled, and the influence of the construction of the deep foundation pit enclosure structure on a high-rise building is reduced; according to the invention, the motor can vibrate the inner shell up and down and shear impurities between the outer through hole and the inner through hole, so that the impurities in the outer through hole and the inner through hole are prevented from being blocked during liquid drainage, the construction efficiency is improved, and the construction progress is ensured.)

1. A concrete structure of a deep foundation pit drainage device of a slope high-rise building comprises a water suction pump (1), a water suction pipe (2), a fixed pipe (3), an outer shell (4), a motor (5), a first guide groove (6), a first rotary table (7), a first connecting groove (8), a first fixed shaft (9), an inner shell (10), an outer through hole (11), an inner through hole (12), an opening (13), a second guide block (14), a second connecting groove (15), a second fixed shaft (16), a second rotary table (17), a second guide groove (18), a connecting shaft (19) and a first guide block (20);

a water pumping pipe (2) is fixedly connected to an inlet of the water pumping pump (1);

the upper side of the fixed pipe (3) is fixedly connected into the upper side of the outer shell (4), and an outlet at the upper side of the fixed pipe (3) is connected with an inlet of the water pumping pipe (2);

the motor (5) is fixedly connected to the inner portion of the left upper side of the outer shell (4), and a first rotating disc (7) is fixedly connected to an output shaft at the left side of the motor (5);

the first guide groove (6) is vertically arranged in the left upper side of the outer shell (4), and a first guide block (20) is vertically and movably connected in the first guide groove (6);

a longitudinal connecting groove I (8) is arranged in the right upper side of the guide block I (20);

the edge of the left side face of the first rotating disc (7) is fixedly connected with a first fixed shaft (9), and the left side of the first fixed shaft (9) is movably connected into a first connecting groove (8);

the second guide groove (18) is vertically arranged in the right upper side of the outer shell (4), and a second guide block (14) is vertically and movably connected in the second guide groove (18);

a second longitudinal connecting groove (15) is formed in the upper left side of the second guide block (14);

the connecting shaft (19) is movably connected in a transverse hole in the upper side of the outer shell (4), the left shaft end of the connecting shaft (19) is fixedly connected with the right output shaft end of the motor (5), and the right end of the connecting shaft (19) is fixedly connected with a second rotating disc (17);

a second fixed shaft (16) is fixedly connected to the edge of the right side face of the second rotary table (17), and the right side of the second fixed shaft (16) is movably connected into the second connecting groove (15);

the inner shell (10) is vertically and movably connected into the outer shell (4), a plurality of inner through holes (12) are uniformly formed in the peripheral side surfaces of the inner shell (10), the left side and the right side of the top of the inner shell (10) are fixedly connected with the bottoms of the first guide block (20) and the second guide block (14) respectively, and the upper guide hole of the inner shell (10) is movably connected to the outer part of the lower side of the fixed pipe (3);

a plurality of outer through holes (11) are uniformly formed in the side faces of the periphery of the outer shell (4), and an opening (13) is formed in the bottom face of the outer shell (4).

2. The deep foundation pit drainage device for the slope high-rise building according to claim 1, wherein: the central line of the first rotating disc (7) and the central line of the second rotating disc (17) are positioned on the same straight line.

3. The deep foundation pit drainage device for the slope high-rise building according to claim 1, wherein: the central line of the first fixed shaft (9) and the central line of the second fixed shaft (16) are positioned on the same straight line.

4. The deep foundation pit drainage device for the slope high-rise building according to claim 1, wherein: the motor (5) is a double-output-shaft speed reduction motor.

5. A construction method for controlling deformation of a deep foundation pit of a slope high-rise building is characterized by comprising the following steps:

(1) deep foundation pit construction for slope high-rise building

A. Calculating the position displacement of the deep foundation pit of the slope high-rise building, and then constructing a continuous wall and a guide wall of the high-rise building;

B. increasing the clearance width of the guide wall during the construction of the guide wall in the step A, adopting a hydraulic grooving machine with an automatic device, keeping the state parallel to the guide wall after the positioning of the groove wall machine is finished, and then falling into the wall to perform grooving construction;

C. when the groove forming construction in the step B is carried out, firstly, single holes at two ends of the groove section are dug, and then, the middle part is dug to complete the construction of the deep foundation pit of the slope high-rise building;

D. c, reinforcing the substrate of the deep foundation pit of the slope high-rise building in the step C to form a deep foundation pit main body substrate;

E. finally, weakly reinforcing the upper soil body by using a triaxial mixing pile machine;

(2) dewatering construction for deep foundation pit of slope high-rise building

A. The method comprises the following steps of (1) draining water in a soil body by using a vacuum well, calculating the total water consumption of a precipitation experiment and a deep foundation pit, and determining the effective precipitation area of a single well;

B. excavating the earthwork of the high-rise building of the side slope;

C. stopping excavating at the bottom of the concrete support during excavating in the step B, then chiseling the super-poured concrete of the underground continuous wall, using a concrete bottom die as the lower part of the support and supporting through pouring concrete, and then pouring a closed substrate of a concrete cushion;

D. finally, mounting a support, applying pre-applied axial force, accurately determining the support position and supporting in time;

(3) drainage construction in deep foundation pit of slope high-rise building

A. Draining water in the deep foundation pit of the slope high-rise building through a drainage device;

B. constructing the structure of the deep foundation pit main body of the slope high-rise building;

C. and B, when the earthwork is excavated to the substrate during construction in the step B, pouring the concrete of the cushion layer for the second time.

6. The construction method for controlling the deformation of the deep foundation pit of the slope high-rise building according to claim 5, wherein the construction method comprises the following steps: and C, during construction of the deep foundation pit in the step C in the construction of the deep foundation pit of the slope high-rise building, controlling the wall brushing quality and controlling soil residues and mud skin between the wall brushing device and the wall brushing device.

7. The construction method for controlling the deformation of the deep foundation pit of the slope high-rise building according to claim 5, wherein the construction method comprises the following steps: and D, reinforcing the mixing pile by drawing strips and skirt cement in the step D in the construction of the deep foundation pit of the slope high-rise building, and then reinforcing by using common silicate cement to form a deep foundation pit main body substrate.

8. The construction method for controlling the deformation of the deep foundation pit of the slope high-rise building according to claim 5, wherein the construction method comprises the following steps: and D, carrying out excavation operation on the excavation in the step B by using an excavator in the precipitation construction of the deep foundation pit of the side slope high-rise building.

9. The construction method for controlling the deformation of the deep foundation pit of the slope high-rise building according to claim 5, wherein the construction method comprises the following steps: the drainage device of claim 1 is adopted in the step C in the drainage construction in the deep foundation pit of the high-rise building on the side slope.

Technical Field

The invention relates to the technical field of building construction, in particular to a construction method for controlling deformation of a deep foundation pit of a slope high-rise building.

Background

The rapid development of urbanization, the population in cities is gradually saturated, land resources are extremely precious, particularly, greening land is used, and due to the situations, the urban high-rise buildings in China are gradually increased. Because of the large number of people, the high-rise building has ever-increasing requirements for air conditioning equipment, storerooms, water supply, power supply and other equipment spaces, and generally has a deep basement, and the high-rise building has stability. There is also a certain demand for the depth of embedment of the building, whereby the depth of the foundation pit is continuously increased. Along with the number of layers of the building is higher and higher, the foundation pit is deeper and deeper, and the enclosure of the deep foundation pit is more and more important.

The deep foundation pit support has two functions of retaining soil and retaining water. The current construction mode mainly adopts sheet pile support or sheet pile anchor, and the two methods have the advantages that the used materials can be recycled, the cost is reduced, but the defects exist. The existing supporting structure can be divided into a pile type supporting system and a gravity supporting system, and the supporting structure and the function are divided into a water permeable retaining structure, a supporting tie part and a water stopping retaining structure according to different construction types.

Disclosure of Invention

The invention aims to provide a construction method for controlling the deformation of a deep foundation pit of a slope high-rise building, which aims to solve the problem that the slope high-rise building deforms when the deep foundation pit is constructed under unfavorable geological conditions.

In order to achieve the purpose, the invention provides the following technical scheme: the construction method for controlling the deformation of the deep foundation pit of the slope high-rise building has the innovation points that the construction method comprises the following steps:

(1) deep foundation pit construction for slope high-rise building

A. Calculating the position displacement of the deep foundation pit of the slope high-rise building, and then constructing a continuous wall and a guide wall of the high-rise building;

B. increasing the clearance width of the guide wall during the construction of the guide wall in the step A, adopting a hydraulic grooving machine with an automatic device, keeping the state parallel to the guide wall after the positioning of the groove wall machine is finished, and then falling into the wall to perform grooving construction;

C. when the groove forming construction in the step B is carried out, firstly, single holes at two ends of the groove section are dug, and then, the middle part is dug to complete the construction of the deep foundation pit of the slope high-rise building;

D. c, reinforcing the substrate of the deep foundation pit of the slope high-rise building in the step C to form a deep foundation pit main body substrate;

E. finally, weakly reinforcing the upper soil body by using a triaxial mixing pile machine;

(2) dewatering construction for deep foundation pit of slope high-rise building

A. The method comprises the following steps of (1) draining water in a soil body by using a vacuum well, calculating the total water consumption of a precipitation experiment and a deep foundation pit, and determining the effective precipitation area of a single well;

B. excavating the earthwork of the high-rise building of the side slope;

C. stopping excavating at the bottom of the concrete support during excavating in the step B, then chiseling the super-poured concrete of the underground continuous wall, using a concrete bottom die as the lower part of the support and supporting through pouring concrete, and then pouring a closed substrate of a concrete cushion;

D. finally, mounting a support, applying pre-applied axial force, accurately determining the support position and supporting in time;

(3) drainage construction in deep foundation pit of slope high-rise building

A. Draining water in the deep foundation pit of the slope high-rise building through a drainage device;

B. constructing the structure of the deep foundation pit main body of the slope high-rise building;

C. and B, when the earthwork is excavated to the substrate during construction in the step B, pouring the concrete of the cushion layer for the second time.

Preferably, in the construction of the deep foundation pit in the step C in the construction of the deep foundation pit of the slope high-rise building, the wall brushing quality is controlled, and soil residues and mud skin between the wall brushing device and the wall brushing device are controlled.

Preferably, in the construction of the deep foundation pit of the slope high-rise building, the stirring pile is reinforced by strip-drawing and skirt cement for the reinforcement in the step D, and then the common silicate cement is used for reinforcement to form the main body substrate of the deep foundation pit.

Preferably, excavating operation is carried out on the excavation in the step B in the precipitation construction of the deep foundation pit of the slope high-rise building by using an excavator.

Preferably, the concrete structure of the drainage device in the step C in the drainage construction in the deep foundation pit of the slope high-rise building comprises a water suction pump, a water suction pipe, a fixed pipe, an outer shell, a motor, a first guide groove, a first rotary table, a first connecting groove, a first fixed shaft, an inner shell, an outer through hole, an inner through hole, an opening, a second guide block, a second connecting groove, a second fixed shaft, a second rotary table, a second guide groove, a connecting shaft and a first guide block; a water pumping pipe is fixedly connected to the inlet of the water pumping pump; the upper side of the fixed pipe is fixedly connected in the upper side of the outer shell, and an outlet at the upper side of the fixed pipe is connected with an inlet of the water pumping pipe; the motor is fixedly connected to the inside of the left upper side of the outer shell, and a first rotating disc is fixedly connected to an output shaft at the left side of the motor; the first guide groove is vertically arranged in the left upper side of the outer shell, and a first guide block is vertically and movably connected in the first guide groove; a longitudinal connecting groove I is formed in the upper right side of the guide block I; the edge of the left side face of the first rotary table is fixedly connected with a first fixed shaft, and the left side of the first fixed shaft is movably connected into the first connecting groove; the second guide groove is vertically arranged in the right upper side of the outer shell, and a second guide block is vertically and movably connected in the second guide groove; a longitudinal connecting groove II is formed in the upper left side of the guide block II; the connecting shaft is movably connected in a transverse hole in the upper side of the outer shell, the left shaft end of the connecting shaft is fixedly connected with the right output shaft end of the motor, and the right end of the connecting shaft is fixedly connected with a second rotating disc; a second fixed shaft is fixedly connected to the edge of the right side face of the second rotary table, and the right side of the second fixed shaft is movably connected into the second connecting groove; the inner shell is vertically and movably connected in the outer shell, a plurality of inner through holes are uniformly formed in the peripheral side surfaces of the inner shell, the left side and the right side of the top of the inner shell are respectively and fixedly connected with the bottoms of the first guide block and the second guide block, and the upper guide hole of the inner shell is movably connected to the outer part of the lower side of the fixed pipe; a plurality of outer through holes are uniformly formed in the side faces of the periphery of the outer shell, and an opening is formed in the bottom face of the outer shell.

Preferably, the central line of the first rotating disc and the central line of the second rotating disc are positioned on the same straight line.

Preferably, the central line of the first fixing shaft and the central line of the second fixing shaft are located on the same straight line.

Preferably, the motor is a dual-output shaft speed reduction motor.

Compared with the prior art, the invention provides a construction method for controlling the deformation of the deep foundation pit of the slope high-rise building, which has the following beneficial effects:

(1) according to the invention, the deep foundation pit main body base is reinforced by the stripping and skirt cement within a certain range through the stirring piles, so that the construction of the enclosure structure can be effectively controlled, and the influence of the construction of the deep foundation pit enclosure structure on a high-rise building is reduced.

(2) According to the invention, the motor can enable the inner shell to vibrate up and down and shear impurities between the outer through hole and the inner through hole, so that the impurities in the outer through hole and the inner through hole are prevented from being blocked during liquid drainage, the construction efficiency is improved, and the construction progress is ensured.

(3) The two turnplates and the fixed shaft arranged in the invention can drive the two sides of the inner shell to move up and down simultaneously, thereby ensuring the stability and reliability of movement, improving the effect of long-time use and avoiding blockage.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a partial enlarged view of the left side of FIG. 1;

FIG. 3 is an enlarged view of a portion of the right side of FIG. 1;

in the figure: 1-a water pump; 2, a water pumping pipe; 3-fixing the tube; 4-an outer shell; 5, a motor; 6, a first guide groove; 7, rotating the first disc; 8, connecting a groove I; 9-fixing the shaft I; 10-an inner housing; 11-outer through hole; 12-inner through hole; 13-opening; 14-a second guide block; 15-connecting groove two; 16-a second fixed shaft; 17-rotating disc II; 18-guide groove two; 19-a connecting shaft; and 20-guide block one.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a technical scheme that: a construction method for controlling deformation of deep foundation pits of a slope high-rise building comprises the following steps:

(1) deep foundation pit construction for slope high-rise building

A. Calculating the position displacement of the deep foundation pit of the slope high-rise building, and then constructing a continuous wall and a guide wall of the high-rise building;

B. increasing the clearance width of the guide wall during the construction of the guide wall in the step A, adopting a hydraulic grooving machine with an automatic device, keeping the state parallel to the guide wall after the positioning of the groove wall machine is finished, and then falling into the wall to perform grooving construction;

C. when the groove forming construction in the step B is carried out, firstly, single holes at two ends of the groove section are dug, and then, the middle part is dug to complete the construction of the deep foundation pit of the slope high-rise building;

D. c, reinforcing the substrate of the deep foundation pit of the slope high-rise building in the step C to form a deep foundation pit main body substrate;

E. finally, weakly reinforcing the upper soil body by using a triaxial mixing pile machine;

(2) dewatering construction for deep foundation pit of slope high-rise building

A. The method comprises the following steps of (1) draining water in a soil body by using a vacuum well, calculating the total water consumption of a precipitation experiment and a deep foundation pit, and determining the effective precipitation area of a single well;

B. excavating the earthwork of the high-rise building of the side slope;

C. stopping excavating at the bottom of the concrete support during excavating in the step B, then chiseling the super-poured concrete of the underground continuous wall, using a concrete bottom die as the lower part of the support and supporting through pouring concrete, and then pouring a closed substrate of a concrete cushion;

D. finally, mounting a support, applying pre-applied axial force, accurately determining the support position and supporting in time;

(3) drainage construction in deep foundation pit of slope high-rise building

A. Draining water in the deep foundation pit of the slope high-rise building through a drainage device;

B. constructing the structure of the deep foundation pit main body of the slope high-rise building;

C. and B, when the earthwork is excavated to the substrate during construction in the step B, pouring the concrete of the cushion layer for the second time.

C, during construction of the deep foundation pit in the step C in construction of the deep foundation pit of the slope high-rise building, controlling the wall brushing quality and controlling soil residues and mud skin between the wall brushing device and the wall brushing device; d, reinforcing the reinforced piles in the step D by drawing strips and skirt cement in the construction of the deep foundation pit of the slope high-rise building, and then reinforcing by using common silicate cement to form a main body substrate of the deep foundation pit; and D, carrying out excavation operation on the excavation in the step B by using an excavator in the precipitation construction of the deep foundation pit of the side slope high-rise building.

As shown in fig. 1-3, the concrete structure of the drainage device in step C in the drainage construction performed in the deep foundation pit of the slope high-rise building includes a water suction pump 1, a water suction pipe 2, a fixed pipe 3, an outer shell 4, a motor 5, a first guide groove 6, a first rotary table 7, a first connecting groove 8, a first fixed shaft 9, an inner shell 10, an outer through hole 11, an inner through hole 12, an opening 13, a second guide block 14, a second connecting groove 15, a second fixed shaft 16, a second rotary table 17, a second guide groove 18, a connecting shaft 19 and a first guide block 20; a water pumping pipe 2 is fixedly connected to an inlet of the water pumping pump 1; the upper side of the fixed pipe 3 is fixedly connected in the upper side of the outer shell 4, and the outlet on the upper side of the fixed pipe 3 is connected with the inlet of the water pumping pipe 2; the motor 5 is fixedly connected to the inside of the left upper side of the outer shell 4, and a first rotating disc 7 is fixedly connected to an output shaft at the left side of the motor 5; the first guide groove 6 is vertically arranged in the upper left side of the outer shell 4, and a first guide block 20 is vertically and movably connected in the first guide groove 6; a longitudinal connecting groove I8 is formed in the upper right side of the guide block I20; the edge of the left side face of the first rotary table 7 is fixedly connected with a first fixed shaft 9, and the left side of the first fixed shaft 9 is movably connected into a first connecting groove 8; the second guide groove 18 is vertically arranged in the right upper side of the outer shell 4, and a second guide block 14 is vertically and movably connected in the second guide groove 18; a second longitudinal connecting groove 15 is formed in the upper left side of the second guide block 14; the connecting shaft 19 is movably connected in a transverse hole in the upper side of the outer shell 4, the left shaft end of the connecting shaft 19 is fixedly connected with the right output shaft end of the motor 5, and the right end of the connecting shaft 19 is fixedly connected with a second rotating disc 17; a second fixed shaft 16 is fixedly connected to the edge of the right side face of the second rotary table 17, and the right side of the second fixed shaft 16 is movably connected into a second connecting groove 15; the inner shell 10 is vertically and movably connected in the outer shell 4, a plurality of inner through holes 12 are uniformly formed in the peripheral side surfaces of the inner shell 10, the left side and the right side of the top of the inner shell 10 are respectively fixedly connected with the bottoms of the first guide block 20 and the second guide block 14, and an upper guide hole of the inner shell 10 is movably connected to the outer part of the lower side of the fixed pipe 3; a plurality of outer through holes 11 are uniformly formed in the side surfaces of the periphery of the outer shell 4, and an opening 13 is formed in the bottom surface of the outer shell 4.

The center line of the first rotating disc 7 and the center line of the second rotating disc 17 are positioned on the same straight line; the central line of the first fixing shaft 9 and the central line of the second fixing shaft 16 are positioned on the same straight line; the motor 5 is a double-output shaft speed reducing motor.

The working principle is as follows: firstly, calculating the position displacement of a deep foundation pit of a slope high-rise building; when the construction is carried out, firstly, the high-rise building continuous wall is constructed, the clearance width of the guide wall is increased when the guide wall is constructed, and after the positioning of the wall-slotting machine is finished, the hydraulic grooving machine adopting an automatic device keeps a state parallel to the guide wall and then falls into the wall; during grooving, firstly excavating single holes at two ends of a groove section, then excavating the middle part, controlling the wall brushing quality during construction of a deep foundation pit, and controlling soil residues and mud skins between the wall brushing device and the wall brushing device; reinforcing the foundation of the deep foundation pit of the slope high-rise building, reinforcing the mixing pile by using drawn strips and skirt cement, and forming a main foundation of the deep foundation pit by using common portland cement; then, utilizing a triaxial mixing pile machine to perform weak reinforcement on the upper soil body; dewatering the deep foundation pit of the slope high-rise building by using a vacuum well to drain water in soil, calculating the total water consumption of a dewatering experiment and the deep foundation pit, and determining the effective dewatering area of a single well; excavating the earthwork of the high-rise building of the side slope and installing supports, performing excavation operation by using an excavator, stopping excavation at the bottom of the concrete support, chiseling out super-cast concrete of the underground continuous wall, using a concrete bottom die as the lower part of the support, then casting the concrete support, and then casting a closed substrate of a concrete cushion; mounting a support and applying a pre-applied axial force; accurately determining a supporting position and supporting in time; draining water in the deep foundation pit of the high-rise building with the side slope through a drainage device; constructing the structure of the deep foundation pit main body of the slope high-rise building, and pouring concrete of a cushion layer for 2 times after earthwork is excavated to the base; the deep foundation pit main body base is reinforced by the aid of the draw bars and the skirt cement within a certain range through the stirring piles, construction of the building enclosure can be effectively controlled, and influence of the construction of the deep foundation pit building enclosure on a high-rise building is reduced; and among the drainage device starter motor 5 can order about carousel one 7 and carousel two 17 rotatory together, and the rotation of carousel one 7 and carousel two 17 then drives guide block one 20 and guide block two 14 through the fixed axle respectively and moves repeatedly from top to bottom together, just also drives interior casing 10 and vibrates from top to bottom and cuts the impurity between outer through-hole 11 and the interior through-hole 12, thereby impurity in outer through-hole 11 and the interior through-hole 12 can not block up when having ensured the flowing back, has just also improved the efficiency of construction and has guaranteed the progress of construction.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.