CN110805076B - Test device and method for simulating reinforcement of passive area of foundation pit - Google Patents

Test device and method for simulating reinforcement of passive area of foundation pit Download PDF

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Publication number
CN110805076B
CN110805076B CN201911182332.5A CN201911182332A CN110805076B CN 110805076 B CN110805076 B CN 110805076B CN 201911182332 A CN201911182332 A CN 201911182332A CN 110805076 B CN110805076 B CN 110805076B
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soil
upright post
retaining wall
retaining
reinforcement
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CN110805076A (en
Inventor
王启云
项玉龙
张丙强
戴忆帆
高居武
肖南雄
林华明
魏心星
臧万军
陈军浩
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Fujian Erjian Architecture Construction Group Co
Fujian University of Technology
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Fujian Erjian Architecture Construction Group Co
Fujian University of Technology
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    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D33/00Testing foundations or foundation structures
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D17/00Excavations; Bordering of excavations; Making embankments
    • E02D17/02Foundation pits
    • E02D17/04Bordering surfacing or stiffening the sides of foundation pits
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D29/00Independent underground or underwater structures; Retaining walls
    • E02D29/02Retaining or protecting walls
    • E02D29/0258Retaining or protecting walls characterised by constructional features
    • E02D29/0266Retaining or protecting walls characterised by constructional features made up of preformed elements
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D2300/00Materials
    • E02D2300/0004Synthetics
    • E02D2300/0018Cement used as binder
    • E02D2300/002Concrete
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D2600/00Miscellaneous
    • E02D2600/20Miscellaneous comprising details of connection between elements

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  • Engineering & Computer Science (AREA)
  • Mining & Mineral Resources (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Paleontology (AREA)
  • Civil Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Environmental & Geological Engineering (AREA)
  • Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)
  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)

Abstract

The invention discloses a test device and a test method for simulating reinforcement of a passive area of a foundation pit, wherein the test device comprises a test box, a supporting member, a reinforcing member and a test unit; the test box can simulate a soil structure; the supporting member can apply or remove prestress to the soil body; the reinforcement member can realize soil reinforcement of a passive area of the foundation pit; the test unit is arranged on the backfill soil surface, the retaining wall surface and the supporting member and is used for monitoring earth surface subsidence, lateral displacement of the retaining wall, soil pressure change conditions on two sides of the retaining wall in the excavation process and stress strain of the retaining wall and the supporting member. The invention can simulate the soil excavation and supporting process after the passive area of the foundation pit is reinforced, can well simulate the supporting effect of the inner support and the reinforcing efficiency of the passive area reinforcement, and can obtain the supporting structure and the surrounding environmental stress and deformation condition of the foundation pit through monitoring; the invention has simple structure, convenient operation and convenient popularization and use.

Description

Test device and method for simulating reinforcement of passive area of foundation pit
Technical Field
The invention relates to the field of geotechnical engineering, in particular to a test device and a test method for simulating reinforcement of a passive area of a foundation pit.
Background
In recent years, with the development and utilization of urban underground space, foundation pit engineering is developed to a direction of larger scale, deeper depth and more complex geological conditions and construction environment, and the influence range and influence degree of foundation pit excavation on the surrounding environment are also larger and larger, especially, deep foundation pits are excavated in weak water-rich stratum. Currently, foundation pit design concepts have been significantly transformed from strength control to deformation control. How to control the deformation of the supporting structure caused by the excavation of the foundation pit and reduce the environmental influence is the primary content in the implementation process of foundation pit engineering. Practice shows that foundation pit deformation cannot be effectively controlled by simply relying on a supporting structure in a soft soil field. The soil body reinforcement can obviously improve the physical and mechanical property indexes of soft soil, thereby achieving the purpose of controlling the deformation of the supporting structure and the ground subsidence, and the passive zone reinforcement is widely applied in foundation pit engineering practice in recent years, and the main types adopted for reinforcement are full-hall reinforcement, strip drawing reinforcement, grid reinforcement and the like. However, there is no clear reference for the current specifications and related manuals how to reasonably determine the reinforcement range and how to consider the problems of the reinforcement soil in the design calculation. Therefore, researchers at home and abroad develop a great deal of research on the reinforcement of the passive area of the foundation pit, and the adopted main methods include numerical calculation, field actual measurement, theoretical analysis and the like. Because of numerous influence factors and complex relationships of soft soil foundation pit deformation, the theory of influence on the foundation pit after the passive region is reinforced is quite weak, meanwhile, calculation parameters in numerical analysis are difficult to accurately select, and numerical calculation results are often questionable. In addition, the on-site monitoring difficulty is high, the cost is high, and real-time comparison analysis of various working conditions cannot be achieved. The model test can strictly control main test parameters and simulate actual conditions to the greatest extent, and is a common means for solving the problem of large-scale complex geotechnical engineering. Therefore, it is necessary to develop a model test device and a method capable of simulating the influence of soil reinforcement in a passive area of a foundation pit on a supporting structure and surrounding environment.
Disclosure of Invention
The invention aims to provide a test device and a test method for simulating reinforcement of a passive area of a foundation pit.
In order to achieve the above purpose, the technical scheme of the invention is as follows: an experimental device for simulating reinforcement of a passive area of a foundation pit comprises a test box, a supporting member, a reinforcing member and a test unit;
The test box comprises a base, a first upright post, a second upright post and a third upright post are sequentially arranged on one side of the upper end surface of the base, a fourth upright post, a fifth upright post and a sixth upright post are correspondingly arranged on the other side of the upper end surface of the base, a soil retaining plate is arranged between the first upright post and the second upright post, between the first upright post and the fourth upright post, between the fourth upright post and the fifth upright post, between the second upright post and the third upright post, between the fifth upright post and the sixth upright post, a vertically laminated soil retaining short plate is arranged, a soil retaining wall is fixedly arranged between the second upright post and the fifth upright post, a plurality of first threaded through holes are uniformly arranged on the soil retaining wall, a vertically laminated soil retaining beam is arranged between the third upright post and the sixth upright post, and a second threaded through hole corresponding to the threaded through holes is arranged on the soil retaining beam; the retaining wall and the retaining plate form a first cavity, the retaining wall, the retaining beam and the retaining short plate form a second cavity, and backfill soil is arranged in the first cavity and the second cavity;
The supporting member comprises a first connecting rod and a second connecting rod which are coaxial and are not connected, one end of the first connecting rod is arranged in the first threaded through hole, a pre-tightening spring, a spring pressing block and a limit nut are sleeved on the outer edge of the first connecting rod in sequence in the direction away from the first threaded through hole, a loading barrel is sleeved outside the spring pressing block, the tail end of the loading barrel is in threaded connection with one end of the second connecting rod, the tail end of the second connecting rod is arranged in the second threaded through hole, the loading barrel is rotated, the loading barrel drives the spring pressing block to slide along the first connecting rod, so that the spring pressing block extrudes or is far away from the spring, and the supporting force formed by the spring pre-tightening on the retaining wall is changed;
The reinforcing member comprises a supporting rod with external threads at two ends, two ends of the supporting rod are respectively arranged in the corresponding first threaded through hole and second threaded through hole, a force transmission plate is sleeved outside one end, close to the first threaded through hole, of the supporting rod, the supporting rod is in threaded connection with the force transmission plate, and supporting force is applied to the retaining wall through the force transmission plate;
The test unit comprises a plurality of electronic displacement meters, a soil pressure box and strain gauges, wherein the electronic displacement meters are respectively arranged on the surface of backfill soil and the surface of the retaining wall and are used for monitoring surface subsidence and lateral displacement of the retaining wall; the soil pressure boxes are respectively arranged at two sides of the retaining wall and used for monitoring the soil pressure change condition at two sides of the retaining wall in the excavation process; the strain gauge is arranged on the retaining wall and the second connecting rod respectively and is used for monitoring stress strain of the retaining wall and the supporting member in the foundation pit excavation process.
Further, a groove is formed in the base, and the lower end of the soil retaining plate is embedded in the groove.
Furthermore, the soil retaining plate is made of toughened organic glass, and soil deep lines are marked on the toughened organic glass.
Further, the inner sides of the second upright post and the fifth upright post are respectively provided with a vertical groove, and the retaining wall is arranged in the vertical grooves of the second upright post and the fifth upright post.
Further, the retaining wall adopts a particle concrete sheet; and filling gaps among the particulate concrete thin plates, the second upright post and the fifth upright post with mortar, and simulating the lateral boundary conditions of the underground diaphragm wall.
Further, a handle is arranged on the loading cylinder.
A test method of a test device for simulating reinforcement of a passive area of a foundation pit comprises the following steps:
S1, mounting a test box
The base is positioned horizontally, a test box is installed, and sealing treatment is carried out on the construction connection position;
s2, reinforcement member selection
According to the actual working condition, the rigidity K of the single supporting rod in the unit reinforcing area is calculated as follows:
K=( m2-m1) S
Wherein m 1 is the proportionality coefficient of the elastic resistance coefficient of the soil body before reinforcement, m 2 is the proportionality coefficient of the elastic resistance coefficient of the soil body after reinforcement, and S is the cross-sectional area of the reinforced soil body corresponding to the single supporting rod;
selecting a support bar according to the calculated rigidity;
S3, soil backfilling
Uniformly arranging a plurality of soil pressure boxes, electronic displacement meters and strain gauges on two sides of the soil retaining plate, and respectively layering and filling soil bodies in the first cavity and the second cavity and compacting the soil bodies; when filling the soil into a reinforced area required by construction, firstly installing a plurality of reinforcing members between the retaining wall and the retaining beam according to the construction requirement, filling soil body, and compacting by adopting a vibration compacting mode; backfilling the first cavity layer by layer upwards, and arranging a plurality of electronic displacement meters on the upper surface of backfill soil in the first cavity after the filling is completed; and sticking strain gauges on the inner support simulation units.
S4, excavation of foundation pit
Removing the uppermost layer of retaining beam and retaining short plate, discharging the backfill soil, arranging an electronic displacement meter in the supporting member according to the construction requirement, arranging the mounted supporting member in threaded through holes corresponding to the retaining wall and the retaining beam, rotating the loading cylinder, and detecting the supporting force of the supporting member through the strain gauge until the supporting force reaches the construction requirement; repeating the soil excavation and the installation steps of the supporting members, and constructing downwards layer by layer; when the foundation pit is excavated to the reinforced area, firstly discharging soil in the reinforced area, and then dismantling the reinforced member according to construction requirements; and after the reinforcement member is removed, continuing the soil excavation and the installation steps of the support member until the soil excavation is completed.
S5, analyzing results
In the whole foundation pit excavation process, special equipment is adopted to record monitoring data of an electronic displacement meter, a soil pressure box and a strain gauge, and stress and deformation rules of the foundation pit after the passive area is reinforced are obtained through arrangement analysis.
The beneficial effects of the invention are as follows: the invention can simulate the soil excavation and supporting process after the passive area of the foundation pit is reinforced, can well simulate the supporting effect of the inner support and the reinforcing efficiency of the passive area reinforcement, and can obtain the supporting structure and the surrounding environmental stress and deformation condition of the foundation pit through monitoring; the inner support simulation unit can realize free loading and unloading of supporting force, and is closer to the engineering practice condition; the soil body reinforcement simulation units can be freely combined, can simulate the influence of different parameters such as reinforcement depth, reinforcement width, reinforcement strength and the like on the foundation pit, and can realize accurate control of excavation of a reinforcement area; the side earth-retaining steel bars are temporarily adopted on the inner side of the foundation pit, the side earth-retaining steel bars can be removed in advance during excavation, foundation pit excavation is carried out from the side, operation is convenient, the traditional earth excavation mode from the upper side of the soil body is changed, and operation intensity is obviously reduced. The invention has simple structure, convenient operation and convenient popularization and use.
Drawings
FIG. 1 is a schematic diagram of the structure of the present invention;
FIG. 2 is a top view of the present invention;
FIG. 3 is a schematic view of the structure of the base;
FIG. 4 is a schematic structural view of a support member;
FIG. 5 is a schematic view of the construction of a retaining wall;
FIG. 6 is a side view of a retaining wall;
100, test chambers; 200. a support member; 300. a reinforcing member; 400. a test unit; 101. a base; 102. a first upright; 103. a second upright; 104. a third upright; 105. a fourth upright; 106. a fifth upright; 107. a sixth upright; 108. a soil retaining plate; 109. a groove; 110. a soil-retaining short plate; 111. a retaining wall; 112. a vertical groove; 113. a retaining beam; 201. a first connecting rod; 202. a second connecting rod; 203. a spring; 204. a spring pressing block; 205. a limit nut; 206. a loading cylinder; 207. a handle; 301. a support rod; 302. a force transfer plate; 401. an electronic displacement meter; 402. a soil pressure box; 403. strain gage.
Detailed Description
The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.
As shown in fig. 1, an experimental apparatus for simulating reinforcement of a passive area of a foundation pit includes a test box 100, a supporting member 200, a reinforcement member 300, and a test unit 400;
The test box can simulate a soil structure, the test box 100 comprises a base 101, a first upright post 102, a second upright post 103 and a third upright post 104 are sequentially arranged on one side of the upper end surface of the base 101, a fourth upright post 105, a fifth upright post 106 and a sixth upright post 107 are correspondingly arranged on the other side of the upper end surface of the base 101, a retaining plate 108 is arranged between the first upright post 102 and the second upright post 103, between the first upright post 102 and the fourth upright post 105 and between the fourth upright post 105 and the fifth upright post 106, a groove 109 is formed in the base 101, and the lower end of the retaining plate 108 is embedded in the groove 109; the soil retaining plate 108 is made of toughened organic glass, and soil deep score lines are marked on the toughened organic glass; a vertical laminated soil-blocking short plate 110 is arranged between the second upright post 103 and the third upright post 104 and between the fifth upright post 106 and the sixth upright post 107, a soil-blocking wall 111 is fixed between the second upright post 103 and the fifth upright post 106, the soil-blocking wall 111 adopts a particle concrete sheet, vertical grooves 112 are formed in the inner sides of the second upright post 103 and the fifth upright post 106, the soil-blocking wall 111 is arranged in the vertical grooves 112 of the second upright post 103 and the fifth upright post 106, and gaps between the soil-blocking wall 111 and the second upright post 103 and the fifth upright post 106 are filled with mortar to simulate the lateral boundary conditions of the underground continuous wall; a plurality of first threaded through holes (not shown in the figure) are uniformly arranged on the retaining wall 111, a vertically laminated retaining beam 113 is arranged between the third upright post 104 and the sixth upright post 107, and a second threaded through hole (not shown in the figure) corresponding to the threaded through holes is arranged on the retaining beam 113; the retaining wall 111 and the retaining plate 108 form a first cavity, the retaining wall 111, the retaining beams and the retaining short plates 110 form a second cavity, and backfill is arranged in the first cavity and the second cavity;
The supporting member can apply or remove prestress to soil, the supporting member 200 comprises a first connecting rod 201 and a second connecting rod 202 which are coaxial and are not connected, one end of the first connecting rod 201 is arranged in a first threaded through hole, a pre-tightening spring 203, a spring pressing block 204 and a limit nut 205 are sleeved outside the first connecting rod 201 in sequence along the direction far away from the first threaded through hole, a loading barrel 206 is sleeved outside the spring pressing block 204, the tail end of the loading barrel 206 is in threaded connection with one end of the second connecting rod 202, the tail end of the second connecting rod 202 is arranged in a second threaded through hole, a handle 207 is arranged on the loading barrel 206, the loading barrel 206 is rotated, the loading barrel 206 drives the spring pressing block 204 to slide along the first connecting rod 201, so that the spring pressing block 204 is extruded or far away from the spring 203, and the supporting force formed by the retaining wall 111 due to the pre-tightening of the spring 203 is changed;
the reinforcement member can realize soil reinforcement of a passive area of a foundation pit, the reinforcement member 300 comprises a support rod 301 with external threads at two ends, two ends of the support rod 301 are respectively arranged in a corresponding first threaded through hole and a corresponding second threaded through hole, a force transmission plate 302 is sleeved outside one end, close to the first threaded through hole, of the support rod 301, the support rod 301 is in threaded connection with the force transmission plate 302, and supporting force is applied to the retaining wall 111 through the force transmission plate 302;
The test unit 400 comprises a plurality of electronic displacement meters 401, a soil pressure box 402 and strain gauges 403, wherein the electronic displacement meters 401 are respectively arranged on the backfill soil surface and the surface of the retaining wall 111 and are used for monitoring the surface subsidence and the lateral displacement of the retaining wall 111; the soil pressure boxes 402 are respectively arranged at two sides of the retaining wall 111 and are used for monitoring the change condition of soil pressure at two sides of the retaining wall 111 in the process of excavation; strain gauges 403 are respectively disposed on the retaining wall 111 and the second connecting rod 202, and are used for monitoring stress strain of the retaining wall 111 and the supporting member 200 during the excavation process of the foundation pit.
The invention can simulate the soil excavation and supporting process after the passive area of the foundation pit is reinforced, can well simulate the supporting effect of the inner support and the reinforcing efficiency of the passive area reinforcement, and can obtain the supporting structure and the surrounding environmental stress and deformation condition of the foundation pit through monitoring; the inner support simulation unit can realize free loading and unloading of supporting force, and is closer to the engineering practice condition; the soil body reinforcement simulation units can be freely combined, can simulate the influence of different parameters such as reinforcement depth, reinforcement width, reinforcement strength and the like on the foundation pit, and can realize accurate control of excavation of a reinforcement area; the side earth-retaining steel bars are temporarily adopted on the inner side of the foundation pit, the side earth-retaining steel bars can be removed in advance during excavation, foundation pit excavation is carried out from the side, operation is convenient, the traditional earth excavation mode from the upper side of the soil body is changed, and operation intensity is obviously reduced. The invention has simple structure, convenient operation and convenient popularization and use.
The test method for the test device for simulating the reinforcement of the passive area of the foundation pit comprises the following steps:
S1, mounting of test chamber 100
The base 101 is positioned horizontally, the test box 100 is installed, and the construction connection position is subjected to sealing treatment;
S2, reinforcement member 300 selection
According to the actual working conditions, the rigidity K of the single supporting rod 301 in the unit reinforcing area is calculated as follows:
K=( m2-m1) S
wherein m1 is the proportionality coefficient of the elastic resistance coefficient of the soil body before reinforcement, m2 is the proportionality coefficient of the elastic resistance coefficient of the soil body after reinforcement, and S is the cross-sectional area of the reinforced soil body corresponding to the single supporting rod 301;
selecting a support bar 301 according to the calculated rigidity;
S3, soil backfilling
A plurality of soil pressure boxes 402, electronic displacement meters 401 and strain gauges 403 are uniformly arranged on two sides of the soil retaining plate 108, and soil is filled and compacted in the first cavity and the second cavity respectively in a layering manner; when filling the soil into the reinforced area required by construction, firstly installing a plurality of reinforcing members 300 between the retaining wall 111 and the retaining beam according to the construction requirement, filling the soil body, and compacting by adopting a vibration compacting mode; backfilling layer by layer upwards, and after the filling is completed, arranging a plurality of electronic displacement meters 401 on the upper surface of backfill soil in the first cavity; and sticking strain gauges on the inner support simulation units.
S4, excavation of foundation pit
Removing the uppermost layer of retaining beams and retaining short plates 110, discharging the layer of backfill, arranging an electronic displacement meter 401 in the supporting member 200 according to the construction requirement, arranging the mounted supporting member 200 in threaded through holes corresponding to the retaining wall 111 and the retaining beams, rotating the loading barrel 206, and detecting the supporting force of the supporting member 200 through the strain gauge 403 until the supporting force reaches the construction requirement; repeating the soil excavation and the installation steps of the supporting member 200, and constructing downwards layer by layer; when the foundation pit is excavated to the reinforced area, firstly discharging soil mass of the reinforced area, and then dismantling the reinforcing member 300 according to construction requirements; after the reinforcement member 300 is removed, continuing the soil excavation and the installation steps of the support member 200 until the soil excavation is completed;
S5, analyzing results
In the whole foundation pit excavation process, special equipment is adopted to record monitoring data of an electronic displacement meter 401, a soil pressure box 402 and a strain gauge 403, and stress and deformation rules of the foundation pit after the passive area is reinforced are obtained through arrangement analysis.
The described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to fall within the scope of the invention.

Claims (4)

1. The test device for simulating the reinforcement of the passive area of the foundation pit is characterized by comprising a test box, a supporting member, a reinforcing member and a test unit;
The test box comprises a base, a first upright post, a second upright post and a third upright post are sequentially arranged on one side of the upper end surface of the base, a fourth upright post, a fifth upright post and a sixth upright post are correspondingly arranged on the other side of the upper end surface of the base, a soil retaining plate is arranged between the first upright post and the second upright post, between the first upright post and the fourth upright post, between the fourth upright post and the fifth upright post, between the second upright post and the third upright post, between the fifth upright post and the sixth upright post, a vertically laminated soil retaining short plate is arranged, a soil retaining wall is fixedly arranged between the second upright post and the fifth upright post, a plurality of first threaded through holes are uniformly arranged on the soil retaining wall, a vertically laminated soil retaining beam is arranged between the third upright post and the sixth upright post, and a second threaded through hole corresponding to the threaded through holes is arranged on the soil retaining beam; the retaining wall and the retaining plate form a first cavity, the retaining wall, the retaining beam and the retaining short plate form a second cavity, and backfill soil is arranged in the first cavity and the second cavity;
The supporting member comprises a first connecting rod and a second connecting rod which are coaxial and are not connected, one end of the first connecting rod is arranged in the first threaded through hole, a pre-tightening spring, a spring pressing block and a limit nut are sleeved on the outer edge of the first connecting rod in sequence in the direction away from the first threaded through hole, a loading barrel is sleeved outside the spring pressing block, the tail end of the loading barrel is in threaded connection with one end of the second connecting rod, the tail end of the second connecting rod is arranged in the second threaded through hole, the loading barrel is rotated, the loading barrel drives the spring pressing block to slide along the first connecting rod, so that the spring pressing block extrudes or is far away from the spring, and the supporting force formed by the spring pre-tightening on the retaining wall is changed;
The reinforcing member comprises a supporting rod with external threads at two ends, two ends of the supporting rod are respectively arranged in the corresponding first threaded through hole and second threaded through hole, a force transmission plate is sleeved outside one end, close to the first threaded through hole, of the supporting rod, the supporting rod is in threaded connection with the force transmission plate, and supporting force is applied to the retaining wall through the force transmission plate;
The test unit comprises a plurality of electronic displacement meters, a soil pressure box and strain gauges, wherein the electronic displacement meters are respectively arranged on the surface of backfill soil and the surface of the retaining wall and are used for monitoring surface subsidence and lateral displacement of the retaining wall; the soil pressure boxes are respectively arranged at two sides of the retaining wall and used for monitoring the soil pressure change condition at two sides of the retaining wall in the excavation process; the strain gauge is respectively arranged on the retaining wall and the second connecting rod and is used for monitoring stress strain of the retaining wall and the supporting member in the foundation pit excavation process;
the base is provided with a groove, and the lower end of the soil retaining plate is embedded in the groove;
the soil retaining plate is made of toughened organic glass, and soil deep score lines are marked on the toughened organic glass;
The retaining wall is arranged in the vertical grooves of the second upright post and the fifth upright post.
2. The test device for simulating reinforcement of a passive area of a foundation pit according to claim 1, wherein the retaining wall is made of a thin slab of particulate concrete, and gaps between the thin slab of particulate concrete and the second and fifth columns are filled with mortar.
3. A test device for simulating reinforcement of a passive area of a foundation pit according to claim 1, wherein the loading cylinder is provided with a handle.
4. A test method of a test device for simulating passive zone reinforcement of a foundation pit according to any one of claims 1-3, comprising the steps of:
S1, mounting a test box
The base is positioned horizontally, a test box is installed, and sealing treatment is carried out on the connecting position of the components;
s2, reinforcement member selection
According to the actual working condition, the rigidity K of the single supporting rod in the unit reinforcing area is calculated as follows:
K=( m2-m1) S
Wherein m 1 is the proportionality coefficient of the elastic resistance coefficient of the soil body before reinforcement, m 2 is the proportionality coefficient of the elastic resistance coefficient of the soil body after reinforcement, and S is the cross-sectional area of the reinforced soil body corresponding to the single supporting rod;
selecting a support bar according to the calculated rigidity;
S3, soil backfilling
Uniformly arranging a plurality of soil pressure boxes, electronic displacement meters and strain gauges on two sides of the soil retaining plate, and respectively layering and filling soil bodies in the first cavity and the second cavity and compacting the soil bodies; when filling the soil into a reinforced area required by construction, firstly installing a plurality of reinforcing members between the retaining wall and the retaining beam according to the construction requirement, filling soil body, and compacting by adopting a vibration compacting mode; backfilling the first cavity layer by layer upwards, and arranging a plurality of electronic displacement meters on the upper surface of backfill soil in the first cavity after the filling is completed;
s4, excavation of foundation pit
Removing the uppermost layer of retaining beam and retaining short plate, discharging the backfill soil, arranging an electronic displacement meter in the supporting member according to the construction requirement, arranging the mounted supporting member in threaded through holes corresponding to the retaining wall and the retaining beam, rotating the loading cylinder, and detecting the supporting force of the supporting member through the strain gauge until the supporting force reaches the construction requirement; repeating the soil excavation and the installation steps of the supporting members, and constructing downwards layer by layer; when the foundation pit is excavated to the reinforced area, firstly discharging soil in the reinforced area, and then dismantling the reinforced member according to construction requirements; after the reinforcement member is removed, continuing the soil excavation and the installation steps of the support member until the soil excavation is completed;
S5, analyzing results
In the whole foundation pit excavation process, special equipment is adopted to record monitoring data of an electronic displacement meter, a soil pressure box and a strain gauge, and stress and deformation rules of the foundation pit after the passive area is reinforced are obtained through arrangement analysis.
CN201911182332.5A 2019-11-27 2019-11-27 Test device and method for simulating reinforcement of passive area of foundation pit Active CN110805076B (en)

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