阅读说明：本技术 一种防止卸载土方时既有隧道上浮的方法 (Method for preventing existing tunnel from floating upwards during earthwork unloading ) 是由 蔡敏 束冬青 孟玉 孙昌兴 王春 单灿灿 高小平 钱礼平 郑永磊 陈卫东 于 2019-10-25 设计创作，主要内容包括：本发明公开了一种防止卸载土方时既有隧道上浮的方法,涉及一种基坑施工方法,该方法包括、确定既有隧道正上方需要卸载土方的范围和深度、对既有隧道两侧且处于需要卸载土方外围的土体进行挖掘直至步骤1确定的深度,形成分布在既有隧道两侧的两个施工区域、在两个施工区域分别施工桩体、在两个施工区域中的一个上对处于两个施工区域之间的需要卸载土方的底部进行顶管施工,形成顶管通道、在顶管通道内施工顶梁并分别与步骤3施工的桩体连接形成跨越既有隧道的板凳桩、板凳桩形成后,进行需要卸载土方的开挖。本发明提供的方法,可有效防止进行卸载时既有隧道上浮的弊端,且操作简单。(The invention discloses a method for preventing an existing tunnel from floating upwards when earthwork is unloaded, which relates to a foundation pit construction method and comprises the steps of determining the range and the depth of the earthwork to be unloaded right above the existing tunnel, excavating soil bodies on two sides of the existing tunnel and at the periphery of the earthwork to be unloaded until the depth determined in the step 1, forming two construction areas distributed on two sides of the existing tunnel, respectively constructing pile bodies in the two construction areas, performing pipe jacking construction on the bottom of the earthwork to be unloaded between the two construction areas on one of the two construction areas, forming a pipe jacking channel, constructing top beams in the pipe jacking channel, respectively connecting the top beams with the pile bodies constructed in the step 3 to form bench piles crossing the existing tunnel, and excavating the earthwork to be unloaded after the bench piles are formed. The method provided by the invention can effectively prevent the defect that the existing tunnel floats upwards when unloading is carried out, and is simple to operate.)

1. A method for preventing an existing tunnel from floating upward when unloading earthwork, which is characterized by comprising the following steps:

step 1, determining the range and depth of earthwork needing to be unloaded right above an existing tunnel;

step 2, excavating soil bodies on two sides of the existing tunnel and on the periphery of the earthwork needing to be unloaded until the depth determined in the step 1, and forming two construction areas distributed on two sides of the existing tunnel;

step 3, constructing pile bodies in the two construction areas respectively;

step 4, performing pipe jacking construction on the bottom of the earthwork needing to be unloaded, which is positioned between the two construction areas, in one of the two construction areas to form a pipe jacking channel;

step 5, constructing a top beam in the pipe jacking channel and respectively connecting the top beam with the pile body constructed in the step 3 to form a bench pile crossing the existing tunnel;

and 6, excavating the earthwork needing to be unloaded after the bench piles are formed.

2. The method of claim 1, wherein the earthwork to be unloaded is one or a combination of earthwork on the corresponding earth surface directly above the existing tunnel or earthwork corresponding to an earth surface downward construction excavation pit directly above the existing tunnel.

3. The method according to claim 2, wherein step 5 is specifically:

and (3) forming mutually communicated pipe jacking channels at the depth determined in the step (1) in the pipe jacking construction process, then excavating earthwork in the pipe jacking channels, constructing a top beam tightly jacking the bottom of the hollow pipe jacking channels in the hollow pipe jacking channels, and respectively connecting two ends of the top beam with corresponding pile bodies to form the bench pile spanning the existing tunnel.

Technical Field

The invention relates to a foundation pit excavation method, in particular to a method capable of preventing a tunnel from floating upwards when unloading operation is carried out above an existing tunnel.

Background

The subway is the main way of public transportation in each big city at present, and has the advantages of high stability, punctuality, safety and the like. And the tunnel is a life passage for the subway to quickly convey passengers.

The construction and later maintenance of the tunnel require a great deal of manpower and material resources. The tunnel floating is a common problem in the construction process, so that influence factors can be fully considered in the construction process so as to avoid various problems caused by floating after later construction is finished.

Therefore, the influence factors of the tunnel floating are basically solved after the tunnel is built, and the phenomenon of later floating is avoided. However, when the soil body directly above the existing tunnel is removed or the foundation pit is excavated, people find that the soil body in the foundation pit can arch and float during excavation, and finally the tunnel directly below the foundation pit can float, so that great potential safety hazards are brought to the safe operation of the subway.

Simultaneously, because above-mentioned problem leads to people to dare not handle the soil heap that is in existing tunnel top etc. or carry out the foundation ditch excavation to the soil body of existing tunnel top, has influenced normal building construction.

Therefore, how to avoid the phenomenon of floating caused by the unloading process of excavation of a foundation pit and the like right above the existing tunnel is urgently needed to be solved by the technical personnel in the field.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a method for preventing the existing tunnel from floating upwards in the process of unloading earthwork right above the existing tunnel so as to solve the technical problem of floating upwards of the existing tunnel caused by unloading soil from the earth surface or excavating a foundation pit in the prior art.

The invention is realized by the following technical scheme:

the invention provides a method for preventing an existing tunnel from floating upwards when earthwork is unloaded, which comprises the following steps:

step 1, determining the range and depth of earthwork needing to be unloaded right above an existing tunnel;

step 2, excavating soil bodies on two sides of the existing tunnel and on the periphery of the earthwork needing to be unloaded until the depth determined in the step 1, and forming two construction areas distributed on two sides of the existing tunnel;

step 3, constructing pile bodies in the two construction areas respectively;

step 4, performing pipe jacking construction on the bottom of the earthwork needing to be unloaded, which is positioned between the two construction areas, in one of the two construction areas to form a pipe jacking channel;

step 5, constructing a top beam in the pipe jacking channel and respectively connecting the top beam with the pile body constructed in the step 3 to form a bench pile crossing the existing tunnel;

and 6, excavating the earthwork needing to be unloaded after the bench piles are formed.

Further, the earthwork to be unloaded is one or a combination of earthwork on the earth surface corresponding to the position right above the existing tunnel or earthwork corresponding to the position where the earth surface corresponding to the position right above the existing tunnel is constructed downwards to excavate the foundation pit.

Further, step 5 specifically comprises:

and (3) forming mutually communicated pipe jacking channels at the depth determined in the step (1) in the pipe jacking construction process, then excavating earthwork in the pipe jacking channels, constructing a top beam tightly jacking the bottom of the hollow pipe jacking channels in the hollow pipe jacking channels, and respectively connecting two ends of the top beam with corresponding pile bodies to form the bench pile spanning the existing tunnel.

The invention provides a method for preventing an existing tunnel from floating upwards when earthwork is unloaded, which has the following beneficial effects:

the invention forms two construction areas after excavating the soil body on the two sides of the existing tunnel and at the outer side of the earthwork needing to be unloaded or the earthwork corresponding to the excavation foundation pit, respectively performs pile body construction, and then forms the bench pile crossing the existing tunnel by constructing and connecting the top beams of the two pile bodies after pipe jacking construction, thereby realizing the purpose of pretreatment before excavating the earthwork.

Drawings

FIG. 1 is a schematic view of working condition 1 of embodiment 1;

FIG. 2 is a schematic view of working condition 2 of embodiment 1;

FIG. 3 is a schematic view of working condition 3 of embodiment 1;

FIG. 4 is a schematic view of the working condition 1 of embodiment 2;

FIG. 5 is a schematic view of the working condition 2 of embodiment 2;

FIG. 6 is a schematic view of the working condition 3 of embodiment 2.

Detailed Description

In order to make the technical solutions of the present application better understood by those skilled in the art, the technical solutions of the present application will be clearly and completely described below in conjunction with the embodiments of the present application, and it is obvious that the described embodiments are only some embodiments of the present application, and not all 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 application.

It is noted that the term "comprising" in the description and claims of the present application is intended to cover a non-exclusive inclusion, e.g. a method comprising a list of steps is not necessarily limited to those steps explicitly listed, but may include other steps not explicitly listed or inherent to such methods. The embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail with reference to examples.