阅读说明：本技术 基坑工程中对承压水进行水平隔断处理的工法 (Construction method for carrying out horizontal partition treatment on confined water in foundation pit engineering ) 是由 陈鸿 曹伟飚 孙建军 冯云 刘仁勇 周元元 路嘉锦 于 2020-11-08 设计创作，主要内容包括：本发明公开了一种基坑工程中对承压水进行水平隔断处理的工法,包括以下步骤：沿待开挖的基坑水平面的周长方向设置一圈竖向隔水帷幕；在所述竖向隔水帷幕所围合成的区域底部设置水平人工隔水层；在所述水平人工隔水层上部的承压含水层中打设泄压降水井进行降水泄压,待降水达到要求后,进行所述基坑的开挖,开挖至所述基坑的设计坑底深度；在所述基坑的底部进行垫层施工,在所述基坑内施作内部结构,所述内部结构浇筑完成后,封闭所述泄压降水井。本发明的优点是：从源头上避免了承压水造成的基坑突涌风险,大幅减少了降水对周边环境的不利影响,同时减少了对深层地下水的大量抽取,保护了珍贵的地下水资源。(The invention discloses a construction method for carrying out horizontal partition treatment on confined water in foundation pit engineering, which comprises the following steps: arranging a circle of vertical waterproof curtain along the perimeter direction of a horizontal plane of a foundation pit to be excavated; arranging a horizontal artificial water-resisting layer at the bottom of the area enclosed by the vertical water-resisting curtain; a pressure relief and pressure relief well is arranged in a confined aquifer at the upper part of the horizontal artificial water-resisting layer for dewatering and pressure relief, and after dewatering meets the requirement, the foundation pit is excavated to the designed pit bottom depth of the foundation pit; and constructing a cushion layer at the bottom of the foundation pit, constructing an internal structure in the foundation pit, and sealing the pressure relief dewatering well after the internal structure is poured. The invention has the advantages that: the foundation pit sudden surge risk caused by confined water is avoided from the source, the adverse effect of precipitation on the surrounding environment is greatly reduced, meanwhile, the large amount of deep underground water is reduced, and precious underground water resources are protected.)

1. A construction method for carrying out horizontal partition treatment on confined water in foundation pit engineering is characterized by comprising the following steps: the construction method comprises the following steps:

a. arranging a circle of vertical waterproof curtain along the perimeter direction of a horizontal plane of a foundation pit to be excavated;

b. arranging a horizontal artificial water-resisting layer at the bottom of the area enclosed by the vertical water-resisting curtain;

c. a pressure relief and pressure relief well is arranged in a confined aquifer at the upper part of the horizontal artificial water-resisting layer for dewatering and pressure relief, and after dewatering meets the requirement, the foundation pit is excavated to the designed pit bottom depth of the foundation pit;

d. and constructing a cushion layer at the bottom of the foundation pit, constructing an internal structure in the foundation pit, and sealing the pressure relief dewatering well after the internal structure is poured.

2. The method for horizontally partitioning confined water in foundation pit engineering according to claim 1, wherein the method comprises the following steps: the four edge parts of the horizontal artificial waterproof layer are connected and sealed with the bottom of the vertical waterproof curtain, and the arrangement depth of the vertical waterproof curtain is not less than that of the horizontal artificial waterproof layer.

3. The method for horizontally partitioning confined water in foundation pit engineering according to claim 1 or 2, wherein the method comprises the following steps: the horizontal artificial water-resisting layer is a cement reinforcing body formed by construction of a deep mixing pile or a high-pressure jet grouting pile, and the reinforcing thickness of the cement reinforcing body is not less than 3 m.

4. The method for horizontally partitioning confined water in foundation pit engineering according to claim 1 or 2, wherein the method comprises the following steps: the horizontal artificial water-resisting layer is a freezing and reinforcing body formed by freezing construction of circulating low-temperature saline water or liquid nitrogen in a freezing pipe, the thickness of the freezing and reinforcing body is not less than 2m, and the freezing temperature of the freezing and reinforcing body is not higher than-5 ℃.

Technical Field

The invention relates to the technical field of foundation pit engineering, in particular to a construction method for carrying out horizontal partition treatment on confined water in foundation pit engineering.

Background

In the foundation pit engineering, when the anti-surging checking calculation of the confined water does not meet the requirement, a pipe well needs to be arranged for pumping water and reducing pressure, the pumping of the underground water can cause great influence on the surrounding environment of the foundation pit, and the spirit of saving and exploiting underground water resources is not met. When the requirement for protecting the surrounding environment of the foundation pit is very high and the confined aquifer is very thick and can not be isolated, the influence of precipitation can be relieved to a certain extent only by deepening the waterproof curtain, but the risk of confined water inrush cannot be avoided from the source.

Disclosure of Invention

The invention aims to provide a construction method for carrying out horizontal partition treatment on confined water in foundation pit engineering, which is characterized in that a horizontal partition is formed by manually reinforcing soil, and an upper confined aquifer is sealed together with a vertical waterproof curtain, so that the risk of confined water inrush is avoided from the source.

The purpose of the invention is realized by the following technical scheme:

a construction method for carrying out horizontal partition treatment on confined water in foundation pit engineering is characterized by comprising the following steps: the construction method comprises the following steps:

a. arranging a circle of vertical waterproof curtain along the perimeter direction of a horizontal plane of a foundation pit to be excavated;

b. arranging a horizontal artificial water-resisting layer at the bottom of the area enclosed by the vertical water-resisting curtain;

c. a pressure relief and pressure relief well is arranged in a confined aquifer at the upper part of the horizontal artificial water-resisting layer for dewatering and pressure relief, and after dewatering meets the requirement, the foundation pit is excavated to the designed pit bottom depth of the foundation pit;

d. and constructing a cushion layer at the bottom of the foundation pit, constructing an internal structure in the foundation pit, and sealing the pressure relief dewatering well after the internal structure is poured.

The four edge parts of the horizontal artificial waterproof layer are connected and sealed with the bottom of the vertical waterproof curtain, and the arrangement depth of the vertical waterproof curtain is not less than that of the horizontal artificial waterproof layer.

The horizontal artificial water-resisting layer is a cement reinforcing body formed by construction of a deep mixing pile or a high-pressure jet grouting pile, and the reinforcing thickness of the cement reinforcing body is not less than 3 m.

The horizontal artificial water-resisting layer is a freezing and reinforcing body formed by freezing construction of circulating low-temperature saline water or liquid nitrogen in a freezing pipe, the thickness of the freezing and reinforcing body is not less than 2m, and the freezing temperature of the freezing and reinforcing body is not higher than-5 ℃.

The invention has the advantages that: the foundation pit sudden-surging risk caused by confined water is avoided from the source, the adverse effect of precipitation on the surrounding environment is greatly reduced, meanwhile, the large amount of deep underground water is reduced, precious underground water resources are protected, and the method has very obvious economic and social benefits under the conditions that the current ultra-deep foundation pits are more and face huge confined water sudden-surging risk and higher environmental protection requirements, and is more prominent in economic benefit when applied to projects such as shield working wells, middle air shafts and the like of ultra-deep foundation pits with smaller areas.

Drawings

FIG. 1 is a schematic plan view of a foundation pit according to the present invention;

FIG. 2 is a schematic cross-sectional view of a foundation pit according to the present invention;

FIG. 3 is a schematic view of step a of the method of the present invention;

FIG. 4 is a schematic view of step b of the method of the present invention;

FIG. 5 is a schematic view of step c of the method of the present invention;

FIG. 6 is a schematic view of step d of the method of the present invention.

Detailed Description

The features of the present invention and other related features are described in further detail below by way of example in conjunction with the following drawings to facilitate understanding by those skilled in the art:

as shown in fig. 1-6, the scores are represented as: the foundation pit comprises a foundation pit 1, a vertical waterproof curtain 2, a horizontal artificial waterproof layer 3, a pressure relief dewatering well 4, a support 5, a foundation pit bottom A, a ground B, a non-confined aquifer C, an intermediate layer D and a confined aquifer E.

Example (b): as shown in fig. 1-6, this example specifically relates to a method for performing horizontal partition treatment on confined water in foundation pit engineering, wherein a circle of vertical waterproof curtain 2 is arranged circumferentially on a horizontal plane of a foundation pit 1 to be excavated, the size and shape of a region surrounded by the vertical waterproof curtain 2 are both adapted to the size and shape of the foundation pit 1, and the region surrounded by the vertical waterproof curtain 2 is a closed structure. A horizontal artificial water-resisting layer 3 is arranged at the bottom of an area surrounded by the vertical water-resisting curtain 2, and the peripheral outer edge part of the horizontal artificial water-resisting layer 3 is connected with and sealed with the bottom of the vertical water-resisting curtain 2, so that a closed structure is formed. In addition, since the vertical waterproof curtain 2 must be closed on a plane, it should exceed the bottom of the horizontal artificial waterproof layer 3 in depth.

In this embodiment, as shown in fig. 2, the horizontal artificial water-resisting layer 3 is a reinforced structure, and the reinforced structure is generally formed by cement-based reinforcement or freezing method reinforcement, because it can better block hydraulic permeation replenishment. Wherein, the cement system reinforcement can adopt deep mixing piles or high-pressure JET grouting piles (including double-pipe and triple-pipe high-pressure JET grouting piles, MJS, RJP, N-JET and other processes), the reinforcement thickness is not less than 3m, and the cement mixing amount is not less than 25-30%; the freezing method generally adopts a saline water or liquid nitrogen freezing process and a vertical or horizontal freezing mode, the thickness of a frozen body is not less than 2m, and the temperature of the frozen body is not higher than-5 ℃. In addition, the elevation of the horizontal artificial water-resisting layer 3 should meet the requirement of anti-surge stability of the confined water below the horizontal artificial water-resisting layer 3. Of course, the horizontal artificial water-resisting layer 3 can also adopt other structures, but needs to satisfy the following requirements: and forms a closed structure with the vertical waterproof curtain 2 and can horizontally block the confined aquifer at the upper part and the lower part of the vertical waterproof curtain.

As shown in fig. 2, the soil structure of the present embodiment includes, in order from top to bottom, an unpressurized water-containing layer C, an intermediate layer D, and a confined water-containing layer E, and the intermediate layer D is a confined water-containing layer or an unpressurized water-containing layer. The setting of the artificial water barrier 3 of level can cut off the vertical supply of confined water to divide into upper and lower two-layer with the confined water layer, to the confined water layer on upper strata, by vertical water barrier curtain 2 and the artificial water barrier 3 of level confined water layer seal the confined water who cuts off, accessible pressure release precipitation well 4 carry out precipitation pressure release can, and the confined water has not had the risk of gushing suddenly under the artificial water barrier 3 of level and the cover of overlying soil layer in the confined water layer of lower floor.

In addition, as shown in fig. 3 to 6, the working method of the present embodiment includes the steps of:

a. as shown in fig. 3, a circle of vertical waterproof curtain 2 is arranged on the ground B, the vertical waterproof curtain 2 is vertically arranged along the perimeter direction of the horizontal plane of the foundation pit 1, the vertical waterproof curtain 2 is generally an underground continuous wall, a TRD, a SMW, a CSM, and the like, and can also be used as an enclosure structure, and the area (on the horizontal plane) enclosed by the vertical waterproof curtain 2 is a closed structure;

b. as shown in fig. 4, a soil body near the bottom of the vertical waterproof curtain 2 is reinforced to form a horizontal artificial waterproof layer 3, so that a horizontal partition system can be formed, the range of a reinforced plane generally needs to cover all foundation pits, and a cement system or a freezing reinforcement mode is generally adopted;

c. as shown in fig. 5, after the vertical waterproof curtain 2 and the horizontal artificial waterproof layer 3 are sealed, a pressure relief dewatering well 4 is drilled on a confined aquifer at the upper part of the reinforced soil body 3, pressure relief drainage is performed through the pressure relief dewatering well 4, after dewatering meets the requirement, excavation of the foundation pit 1 is performed until the foundation pit is excavated to the bottom a of the foundation pit, and meanwhile, a support 5 is arranged, so that subsequent cushion layer construction is facilitated;

d. as shown in fig. 6, the bottom of the foundation pit 1 is subjected to cushion layer construction, the internal structure is built back, and after the internal structure is completed, the pressure relief dewatering well 4 is sealed.

In conclusion, according to the embodiment, the sudden gushing risk of the foundation pit caused by confined water can be avoided from the source, the adverse effect of precipitation on the surrounding environment is greatly reduced, meanwhile, the large amount of deep groundwater is reduced, precious groundwater resources are protected, and the method has very obvious economic and social benefits under the conditions that the current ultra-deep foundation pits are more and face huge confined water sudden gushing risk and higher environmental protection requirements, and is more prominent in economic benefit when being applied to projects such as shield work wells, middle air shafts and the like of ultra-deep foundation pits with smaller areas.

Although the conception and the embodiments of the present invention have been described in detail with reference to the drawings, those skilled in the art will recognize that various changes and modifications can be made therein without departing from the scope of the appended claims, and therefore, they are not to be considered repeated herein.