CN114486561B - Tunnel surrounding rock structural surface in-situ shear strength testing system and method - Google Patents
Tunnel surrounding rock structural surface in-situ shear strength testing system and method Download PDFInfo
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- CN114486561B CN114486561B CN202111629753.5A CN202111629753A CN114486561B CN 114486561 B CN114486561 B CN 114486561B CN 202111629753 A CN202111629753 A CN 202111629753A CN 114486561 B CN114486561 B CN 114486561B
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- G01N3/24—Investigating strength properties of solid materials by application of mechanical stress by applying steady shearing forces
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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Abstract
The application provides a tunnel surrounding rock structural surface in-situ shear strength testing system and method. The method comprises the following steps: calculating to obtain the shear strength tau of the structural surface at the position 1 、τ 2 、τ 3 、τ 4 、τ 5 ...; comparison of tau 2 And τ 1 When τ is 2 Not less than the lower threshold value x tau 1 And τ 2 Upper limit threshold value not more than x tau 1 At τ of 2 As an effective value tau for the shear strength of the structural surface there, otherwise tau is compared 3 And τ 2 .. until an effective value τ of the shear strength of the structural surface is obtained. The in-situ shear strength testing system and method for the tunnel surrounding rock structural surface are convenient to construct and test, and can effectively consider the size effect of the shear strength of the structural surface to obtain more accurate shear strength of the structural surface.
Description
Technical Field
The application belongs to the technical field of testing or analyzing materials by means of measuring physical properties of the materials, and particularly relates to an in-situ shear strength testing method for a tunnel surrounding rock structural surface.
Background
The shear strength of the structural surface belongs to structural surface parameters and is one of the most important mechanical parameters in rock engineering mechanics, and the magnitude of the shear strength of the structural surface has important guiding significance for side slope engineering, tunnel engineering and other engineering related to rock mechanics subjects. Particularly, with the continuous development of engineering construction, tunnel engineering faces the threat of high ground stress, and in a structural surface control type tunnel, structural surface parameters often play a main control role.
In the structural surface testing method in the prior art, most of the structural surface testing methods adopt a field sampling laboratory test mode for testing. Or a large-scale horizontal clipper is adopted to obtain a sample with larger size on the spot for experiment.
The above methods all have the following problems: on one hand, the measurement result error caused by detour in the sampling process cannot be avoided, and on the other hand, the influence of the size effect cannot be considered. Therefore, there is a need to provide an improved solution to the above-mentioned deficiencies of the prior art.
Disclosure of Invention
The application aims to provide a system and a method for testing in-situ shear strength of a tunnel surrounding rock structural plane, so as to solve or alleviate the problems in the prior art.
In order to achieve the above purpose, the present application provides the following technical solutions: the in-situ shear strength test system for the tunnel surrounding rock structural surface is used for testing the shear strength of the tunnel surrounding rock structural surface and comprises: a loading assembly, a pressurized oil pump and a monitoring assembly; the loading assembly comprises a steel pipe with a hole and a loading bag; the monitoring assembly comprises a displacement monitoring device and a pressure monitoring device;
one end of the steel pipe with the hole is closed and extends into the loading hole, and a plurality of liquid flowing holes are formed in the side wall of the steel pipe with the hole along the circumferential direction; the loading hole is positioned between two adjacent structural surfaces of the tunnel surrounding rock and extends along the joint trend of the structural surfaces;
the loading bag covers the outer side wall of the steel pipe with the hole, and the input end of the loading bag is hermetically connected with the liquid flowing hole;
the displacement monitoring device is positioned between the loading hole and the inclined hole and is used for monitoring the displacement of the target area in real time; the inclined hole is positioned between two adjacent structural surfaces of the tunnel surrounding rock and extends along the joint trend, and the bottom end of the inclined hole is intersected with the bottom end of the loading hole; the target area is an area formed by two adjacent structural surfaces, the inclined hole and the loading hole;
the pressurizing oil pump is communicated with the outer end of the steel pipe with the hole through a hydraulic oil pipe, and pumps pressure oil into the steel pipe with the hole; the outer end of the steel pipe with the hole is the end, extending out of the loading hole, of the steel pipe with the hole; the pressure oil is transmitted to the loading bag along the liquid flow hole, so that the loading bag is expanded to push the target area to move;
the pressure monitoring device is used for monitoring the pressure of the pressure oil.
Further, the length of the loading capsule is the same as the hole depth of the loading hole.
Further, the axis of the loading hole is perpendicular to the structural plane.
Furthermore, a plurality of liquid flow holes are uniformly distributed on the side wall of the part, extending into the loading hole, of the steel pipe with the hole.
The invention also provides an in-situ shear strength test method for the tunnel surrounding rock structural surface, which comprises the following steps:
s101, determining the diameter of a drill hole according to the vertical distance between an upper structural surface and a lower structural surface;
step S102, according to the determined drilling diameter and the determined interval h between the loading hole and the inclined hole on the joint 1 Constructing a loading hole and an inclined hole at the junction of the upper structural surface and the lower structural surface along the joint direction, and recording the hole depth L of the loading hole 1 The bottom end of the loading hole is intersected with the bottom end of the inclined hole to obtain a joint target area S surrounded by the loading hole and the inclined hole 1 ；
S103, arranging a loading assembly in the loading hole, and arranging a displacement monitoring device for measuring the target area S in real time 1 The moving distance of (a);
step S104, pressurizing the loading assembly through a pressurizing oil pump to expand the loading bag, applying stress to a rock body forming the wall of the loading hole in a mode of gradually increasing pressure, and obtaining a target area S 1 When the change of the movement distance is larger than the displacement threshold value, S is judged 1 The upper and lower structural surfaces are sheared and broken, the pressurized oil pump is stopped, and the maximum pressure value sigma output in the process of the pressurized oil pump is recorded Capsule ；
Step S105, based on the determined sigma Capsule Drilling data, and calculating to obtain S according to the vertical load model 1 When the upper and lower structural surfaces are sheared and damaged, the loading assembly loads the target area S 1 Applied vertical load F 1 Said vertical load F 1 Is perpendicular to the axis of the loading hole;
step S106, based on the determined F 1 Drilling data are combined with a shear strength model, and the shear strength tau of the structural surface is calculated 1 ；
Step S107, obtaining the determined h according to the determined delta h and the drill hole diameter 2 、h 3 、h 4 、h 5 ..., according to h 2 、h 3 、h 4 、h 5 .., under the condition that the included angle of the loading hole and the inclined hole is kept unchanged, the loading hole and the inclined hole are constructed again on the same joint, and a target area S surrounded by the joint, the loading hole and the inclined hole is obtained 2 、S 3 、S 4 、S 5 ......；
Step S108, repeating the steps S103 to S106 to obtain tau 2 、τ 3 、τ 4 、τ 5 ......；
Step S109, comparing τ 2 And τ 1 When τ is 2 Not less than the lower threshold value x tau 1 And τ is 2 Not more than the upper threshold value x tau 1 At τ of 2 As the effective value tau of the shearing strength of the structural surface, otherwise, comparing tau 3 And τ 2 .. until an effective value tau of the shear strength of the structural surface is obtained.
Further, in step S101, the diameter of the drilled hole is equal to the vertical distance d between the upper structural surface and the lower structural surface.
Further, in step S104, the displacement threshold is 4% to 6% of the initial distance between the loading hole and the inclined hole in the joint.
Further, in step S105, the vertical load model is F 1 ＝σ Capsule ×d×L 1 ；
σ Capsule Indicating the pressure within the loading cell and d the vertical distance between the upper and lower structural planes.
Further, in step S106, the shear strength model is τ 1 ＝F 1 /2/(h 1 ×L 1 /2)；
In the formula, F 1 2 represents the vertical load to which a single joint is subjected, h 1 ×L 1 [ 2 ] denotes a target region S 1 The upper surface or the lower surface of (2) and the joint contact area.
Further, in step S109, the upper threshold is 1.03 and the lower threshold is 0.92.
Compared with the closest prior art, the technical scheme of the embodiment of the application has the following beneficial effects:
1) the invention has convenient construction and test, can test the shear strength in situ, and can effectively consider the size effect of the shear strength of the structural surface to obtain more accurate shear strength of the structural surface.
2) The loading bag of the loading assembly extends to the bottom of the vertical hole so as to uniformly pressurize the hole wall of the vertical hole from shallow to deep, and the accuracy of the detection result is better ensured.
3) The steel pipes with holes are uniformly distributed on the side wall extending into the loading hole part, so that the pressure at each part of the pressurizing bag is balanced, and the accuracy of a detection result is ensured.
4) The diameter of the drilled hole is equal to the vertical distance d between the upper structural surface and the lower structural surface, so that the interference of the rock strength on the shear strength test result of the structural surface is avoided.
5) The displacement threshold value is 4% -6% of the initial distance between the loading hole and the inclined hole in the joint, the displacement threshold value is obtained by considering the elastic property and the plastic property of the surrounding rock, and irrelevant interference can be avoided better, so that an accurate shear strength result is obtained.
6) The upper threshold value is 1.03, and the lower threshold value is 0.92, which is a result obtained by considering accidental errors, system errors and rock size effects, and can better avoid irrelevant interference, thereby obtaining an accurate shear strength result.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, are included to provide a further understanding of the application, and the description of the exemplary embodiments of the application are intended to be illustrative of the application and are not intended to limit the application. Wherein:
FIG. 1 is a diagram illustrating an embodiment of the method for testing the in-situ shear strength of the structural surface of the surrounding rock of the tunnel according to the present invention;
FIG. 2 is an enlarged view at A in FIG. 1;
FIG. 3 is a top view of FIG. 2;
FIG. 4 is a partial block diagram of the steel tube with holes of FIG. 1;
FIG. 5 is a schematic diagram of the pressurized oil pump, the loading assembly and the pressure monitoring device of FIG. 1;
FIG. 6 is a schematic view of the schematic structure of FIG. 1;
FIG. 7 is a schematic diagram of the movement of the loading assembly in the area S1 in FIG. 3;
FIG. 8 is a block diagram of the procedure of an embodiment of the method for testing the in-situ shear strength of the structural surface of the surrounding rock of the tunnel according to the present invention;
fig. 9 is a schematic structural diagram of step S106 in fig. 8.
Description of the reference numerals:
1-surrounding rock; 2-joint; 3-upper structural plane; 4-lower structural plane; 5-inclined holes; 6-vertical holes; 7-a steel pipe with holes; 8-displacement monitoring means; 9-a pressurized oil pump; 10-a pressure monitoring device; 11-hydraulic oil pipe; 12-a loading capsule; 13-flow hole.
Detailed Description
The present application will be described in detail below with reference to the accompanying drawings in conjunction with embodiments. Various examples are provided by way of explanation of the present application and not limitation of the present application. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present application without departing from the scope or spirit of the application. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield a still further embodiment. It is therefore intended that the present application encompass such modifications and variations as fall within the scope of the appended claims and their equivalents.
In the description of the present application, the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description of the present application but do not require that the present application be constructed and operated in a particular orientation, and thus should not be construed as limiting the present application. The terms "connected," "connected," and "disposed" as used herein are intended to be broadly interpreted, and may include, for example, fixed connections and removable connections; can be directly connected or indirectly connected through intermediate components; specific meanings of the above terms can be understood as specific cases by those of ordinary skill in the art.
The invention provides a specific embodiment of a method for testing in-situ shear strength of a tunnel surrounding rock structural surface, which is shown in figures 1 to 9, wherein in figure 1, the angle is
The method for testing the in-situ shear strength of the structural surface of the tunnel surrounding rock is an included angle between joints in the surrounding rock 1 and the horizontal direction, and comprises the following steps:
step S101, determining the diameter of a drill hole according to the vertical distance between the upper structural surface 3 and the lower structural surface 4, specifically, the diameter of the drill hole is equal to the vertical distance d between the upper structural surface 3 and the lower structural surface 4, so that the upper structural surface 3 and the lower structural surface 4 are ensured to be equally stressed, and meanwhile, the interference of the rock mass strength on the structural surface shear strength test result is avoided.
Step S102, according to the determined drilling diameter and the determined interval h between the vertical hole 6 and the inclined hole 5 on the joint 2 1 And the axis of the vertical bore 6 is perpendicular to the structural plane. Constructing a vertical hole 6 and an inclined hole 5 at the junction of the upper structural surface and the lower structural surface along the direction of the joint 2, and recording the hole depth L of the vertical hole 6 1 The bottom end of the vertical hole 6 is intersected with the bottom end of the inclined hole 5 to obtain a target area S surrounded by the joint 2, the vertical hole 6 and the inclined hole 5 together 1 . The axis of the vertical hole 6 is perpendicular to the structural plane because when a plurality of holes are repeatedly drilled, the axes of the holes are substantially parallel and parallelThe hole is used for arranging a loading assembly, and the basic level of the axis of each hole is favorable for ensuring the accuracy of a detection result; if when a plurality of holes with inclined axes and structural planes are drilled repeatedly, the axes of the holes are difficult to ensure to be basically parallel, and the loading assembly is arranged in the hole, so that certain influence is brought to the accuracy of the detection result. The vertical holes 6 and the inclined holes 5 must intersect to avoid the structural strength of the surrounding rock from influencing the test result.
Step S103, arranging a loading assembly in the vertical hole 6, wherein a loading bag 12 of the loading assembly extends to the bottom of the vertical hole 6, so that the hole wall of the vertical hole 6 is uniformly pressurized from shallow to deep, and the accuracy of the detection result is better ensured. When the pressurizing oil pump 9 is pressurized, the loading bladder 12 is inflated to push the target area S 1 The whole moves. A displacement monitoring device 8 is arranged between the vertical hole 6 and the inclined hole 5, and the displacement monitoring device 8 is used for measuring a target area S which is surrounded by the joint 2, the vertical hole 6 and the inclined hole 5 together in real time 1 The moving distance of (c); the displacement monitoring device 8 adopts a total station instrument, the detection technology of the total station instrument is mature, and meanwhile, the high precision of the whole measurement can be guaranteed.
Step S104, starting the pressure oil pump 9, pressurizing the loading assembly in the vertical hole 6 through the hydraulic oil pipe 11, expanding the loading bag 12 and uniformly applying stress to rock masses at all positions forming the wall of the vertical hole 6 in a pressure gradually increasing mode, and accordingly pushing the target area S 1 And (4) moving. As shown in fig. 7, the target region S 1 When the change of the movement distance is greater than the displacement threshold value, in this embodiment, the displacement threshold value is 5% of the initial distance between the vertical hole 6 and the inclined hole 5 on the joint 2, (the displacement threshold value is obtained according to the elastic performance and the plastic performance of the surrounding rock so as to avoid the interference of irrelevant factors on the detection result, and according to the elastic performance and the plastic performance of the surrounding rock where the joint is located, the displacement threshold value can be adjusted between 4% and 6%, specifically 4%, 4.5%, 5%, 5.5%, 6%, and the like), and S is judged 1 The upper and lower structural surfaces 3 and 4 are sheared and damaged, the mutually close hole walls of the moved vertical hole 6 and the inclined hole 5 are shown by dotted lines, and the maximum pressure value sigma output by the loading assembly in the process is recorded Capsule ；σ Capsule The pressure in the loading bladder 12 is indicated and measured by a pressure monitoring device 10 provided with the pressurized oil pump 10.
Step S105, based on the determined sigma Capsule Drilling data, and calculating to obtain S according to the vertical load model 1 When the upper and lower structural surfaces are sheared and damaged, the loading assembly loads the target area S 1 Applied vertical load F 1 Vertical load F 1 Is perpendicular to the axis of the loading hole; wherein the vertical load model is F 1 ＝σ Capsule ×d×L 1 That is, the drilling data in this step is L 1 And d;
step S106, based on the determined F 1 And (3) calculating the shear strength tau of the structural surface 2 by combining the drilling data with the shear strength model 1 (ii) a Wherein the shear strength model τ 1 ＝F 1 /2/(h 1 ×L 1 /2), i.e. the drilling data in this step is L 1 And h 1 。
In the formula, F 1 [ 2 ] represents the vertical load to which the upper structural surface 3 or the lower structural surface 4 is subjected, h 1 ×L 1 [ 2 ] indicates the target region S 1 The upper surface or the lower surface of (2) and the joint 2.
Step S107, obtaining the determined h according to the determined value range of 0.3m (the value range of Δ h is 0.2m-0.4m, specifically 0.2m, 0.25m, 0.3m, 0.35m, 0.4m, etc.), if the value range is smaller than this range, the influence of the contingency factors such as large rock mass structure difference on the test result is large, and if the value range is larger than this range, the influence of Δ h on the test result is large), and obtaining the determined h 2 、h 3 、h 4 、h 5 ..., according to h 2 、h 3 、h 4 、h 5 .., and according to the determined drilling diameter (the same as the drilling diameter in the step S102, and a single variable principle is guaranteed), under the condition that the included angle between the vertical hole 6 and the inclined hole is kept unchanged (the same is used for guaranteeing the single variable principle), the vertical hole 6 and the inclined hole 5 are constructed on the same joint 2 again, the depth of the vertical hole 6 is L2, L3, L4 and L5 2 、S 3 、S 4 、S 5 ....... The interval between the holes on the joint 2 in step S107 is not less than 20cm, and the interval between the holes in step S107 and the holes in step S103 is not less than 20cm, so as to avoid interference between adjacent holes.
Step S108, repeating the steps S103 to S106 to obtain tau 2 、τ 3 、τ 4 、τ 5 ......；
Step S109, defining the upper limit threshold value to be 1.08 and the lower limit threshold value to be 0.92, and comparing tau 2 And τ 1 When τ is 2 Not less than the lower threshold value x tau 1 And τ 2 Upper limit threshold value not more than x tau 1 At τ, of 2 As the effective value tau of the shearing strength of the structural surface, otherwise, comparing tau 3 And τ 2 .. until an effective value tau of the shear strength of the structural surface at the position is obtained. The upper threshold value is 1.03, the lower threshold value is 0.92, and the rock size effect, the systematic error and the accidental error are considered to be 2 And τ 1 、τ 3 And τ 2 And the interference caused by the comparison result of the data sets. The rock size effect in this application is: according to theoretical and engineering practical researches, the larger the area of a test area is, the smaller the measured shear strength value is even if the same structural plane is tested. But the difference in shear strength becomes smaller and smaller as the area of the region increases to some extent. According to practical studies, the proportional coefficient of the systematic error and the accidental error is about +/-0.03, so that the upper threshold value is 1+0.03, namely 1.03. The lower threshold value needs to consider the rock size effect, the proportionality coefficient of the rock size effect is approximately-0.05, so that the lower threshold value is 1-0.03-0.05, namely 0.92, the interference of irrelevant factors can be reduced, and a more accurate shear strength result can be obtained.
The invention provides a concrete embodiment of a tunnel surrounding rock structural surface in-situ shear strength testing system, which is used for testing the shear strength of a tunnel surrounding rock structural surface, and as shown in fig. 2 and fig. 3, the system comprises: a loading assembly, a pressurized oil pump 9 and a monitoring assembly. The loading assembly comprises a steel pipe with a hole 7 and a loading bag 12, the length of the loading bag 12 is the same as the hole depth of a loading hole (a vertical hole 6) (the loading bag 12 and the steel pipe with the hole 7 have multiple groups for adapting to different hole depths of the loading hole), and the length of the loading bag 12 is the same as the hole depth of the loading hole and has the function of realizing uniform pressurization on the hole wall of the vertical hole 6 from shallow to deep. The monitoring assembly includes a displacement monitoring device 8 and a pressure monitoring device 10.
One end of the steel pipe with holes 7 is closed and extends into the loading hole, a plurality of liquid flowing holes 13 are formed in the side wall of the steel pipe with holes 7 along the circumferential direction, and liquid in the axial cavity of the steel pipe with holes 7 can be transferred to the input end of a loading bag 12 sleeved outside the steel pipe with holes 7 through the liquid flowing holes 13, so that the loading bag 12 is driven to expand. The diameter of the liquid flowing holes 13 in the steel pipe with holes 7 is 1cm, and the diameter of the liquid flowing holes 13 in the steel pipe with holes is 1cm, so that the structural strength of the steel pipe with holes 7 can be well guaranteed on the premise that the sectional area of the liquid flowing holes 13 can meet the requirement of the injection rate of hydraulic oil, and the steel pipe with holes 7 is prevented from being damaged in a high-pressure environment. Specifically, the plurality of liquid flow holes 13 are uniformly distributed on the side wall of the loading hole part, into which the steel pipe with hole 7 extends, so that the pressure at each part of the pressurizing bag 12 is balanced, and the accuracy of the detection result is guaranteed. The loading bag 12 is coated on the outer side wall of the steel pipe 7 with the hole, the input end of the loading bag 12 is communicated with the liquid flowing hole 13, and the loading bag 12 is in sealing fit with the hole wall of the liquid flowing hole 13, so that liquid leakage is avoided. The loading bag 12 is made of a rubber material with a high expansion coefficient which is not less than 3, so that the influence of the expansion amount of the loading bag 12 exceeding the self expansion capacity on the detection result is avoided. The steel pipe 7 with the hole is detachably connected with a hydraulic oil pipe 11 of the pressure oil pump 9, so that the transportation and the storage are convenient, and the required construction space is small when the in-situ shear strength testing method for the structural surface of the surrounding rock of the tunnel is implemented. The loading cell 12 expands with the continued operation of the pressurized oil pump 9 to apply pressure to the outside, and in this embodiment, the loading cell 12 expands to push the rock mass in the region of S1 to move.
The displacement monitoring device 8 is arranged between the loading hole (vertical hole 6) and the empty hole (inclined hole 5) and is positioned on the rock mass between the upper structural surface 3 and the lower structural surface 4, the displacement monitoring device 8 is actually a whole station instrument and is used for monitoring the moving displacement of a target area in real time, and in the embodiment, the target area is the S-shaped hole 1 、S 2 、S 3 、S 4 、S 5 ....... Monitoring a target area S surrounded by the joint 2, the vertical hole 6 and the inclined hole 5 in real time 1 The moving distance of (2).
The pressure monitoring device 10 is used to monitor the pressure of the pressure oil. The pressure oil pump 9 is connected with the monitoring end of the pressure monitoring device 10, and the output pressure of the pressure oil pump 9, namely the real-time data of the pressure in the loading bag 12, is obtained. The maximum value of the rated output pressure of the pressurizing oil pump 9 is not less than 40MPa so as to meet the detection requirement. The measurement accuracy of the pressure monitoring device 10 is not less than 0.01Mpa, and the measurement error is reduced. Preferably, the steel tube with holes 7 is a seamless steel tube with high strength, the yield strength is not less than 235MPa, and damage to the steel tube under high-pressure environment during detection is avoided.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (6)
1. The utility model provides a tunnel country rock structural plane normal position shear strength test system, it is right to be used for tunnel country rock structural plane carries out the shear strength test, its characterized in that includes: a loading assembly, a pressurized oil pump and a monitoring assembly; the loading assembly comprises a steel pipe with a hole and a loading bag; the monitoring assembly comprises a displacement monitoring device and a pressure monitoring device;
one end of the steel pipe with the hole is closed and extends into the loading hole, and a plurality of liquid flowing holes are formed in the side wall of the steel pipe with the hole along the circumferential direction; the loading hole is positioned between two adjacent structural surfaces of the tunnel surrounding rock and extends along the joint trend of the structural surfaces;
the loading bag covers the outer side wall of the steel pipe with the hole, and the input end of the loading bag is connected with the liquid flowing hole in a sealing mode;
the displacement monitoring device is positioned between the loading hole and the inclined hole and is used for monitoring the moving displacement of the target area in real time; the inclined hole is positioned between two adjacent structural surfaces of the tunnel surrounding rock and extends along the joint trend, and the bottom end of the inclined hole is intersected with the bottom end of the loading hole; the target area is an area formed by two adjacent structural surfaces, the inclined hole and the loading hole;
the pressurized oil pump is communicated with the outer end of the steel pipe with the hole through a hydraulic oil pipe, and pumps pressure oil into the steel pipe with the hole; the outer end of the steel pipe with the hole is the end, extending out of the loading hole, of the steel pipe with the hole; the pressure oil is transmitted to the loading bag along the liquid flow hole, so that the loading bag is expanded to push the target area to move;
the pressure monitoring device is used for monitoring the pressure of the pressure oil.
2. The in-situ shear strength testing system for the structural plane of the surrounding rock of the tunnel of claim 1, wherein the length of the loading bladder is the same as the hole depth of the loading hole.
3. The in-situ shear strength testing system for the structural surface of tunnel surrounding rock according to claim 1, wherein the axis of the loading hole is perpendicular to the structural surface.
4. The in-situ shear strength testing system for the structural surface of the surrounding rock of the tunnel according to any one of claims 1 to 3, wherein a plurality of the liquid flow holes are uniformly distributed on the side wall of the portion, extending into the loading hole, of the steel pipe with holes.
5. An in-situ shear strength testing method for a structural surface of tunnel surrounding rock, which is characterized in that the in-situ shear strength testing system for the structural surface of tunnel surrounding rock of any one of claims 1 to 4 is adopted to test the shear strength of the structural surface of tunnel surrounding rock, and the in-situ shear strength testing method for the structural surface of tunnel surrounding rock comprises the following steps:
s101, determining the diameter of a drill hole according to the vertical distance between an upper structural surface and a lower structural surface;
step S102, according to the determinationAnd according to the determined interval h between the loading hole and the inclined hole on the joint 1 Constructing a loading hole and an inclined hole at the junction of the upper structural surface and the lower structural surface along the joint direction, and recording the hole depth L of the loading hole 1 The bottom end of the loading hole is intersected with the bottom end of the inclined hole to obtain a joint, and a target area S surrounded by the loading hole and the inclined hole together 1 ；
S103, arranging a loading assembly in the loading hole, and arranging a displacement monitoring device for measuring the target area S in real time 1 The moving distance of (a);
step S104, pressurizing the loading assembly through a pressurizing oil pump to expand the loading bag, applying stress to a rock body forming the wall of the loading hole in a mode of gradually increasing pressure, and obtaining a target area S 1 When the change of the movement distance is larger than the displacement threshold value, S is judged 1 The upper and lower structural surfaces are sheared and broken, the pressurizing oil pump is stopped, and the maximum pressure value sigma output in the process of the pressurizing oil pump is recorded Capsule (ii) a Wherein the displacement threshold value is 4% -6% of the initial distance between the loading hole and the inclined hole on the joint;
step S105, based on the determined sigma Capsule Drilling data, and calculating to obtain S according to the vertical load model 1 When the upper and lower structural surfaces are sheared and damaged, the loading assembly loads the target area S 1 Applied vertical load F 1 The vertical load F 1 Is perpendicular to the axis of the loading hole;
the vertical load model is:
F 1 ＝σ capsule ×d×L 1 ；
Wherein: sigma Capsule To load the pressure within the bladder;
d is the vertical distance between the upper structural surface and the lower structural surface;
step S106, based on the determined F 1 Drilling data are combined with a shear strength model, and the shear strength tau of the structural surface at the position is obtained through calculation 1 ；
The shear strength model is:
τ 1 ＝F 1 /2/(h 1 ×L 1 /2)；
wherein: f 1 The/2 is the vertical load to which a single joint is subjected;
h 1 ×L 1 /2 is the target area S 1 The upper surface or the lower surface of (a) and the joint contact area;
step S107, obtaining determined h according to the determined delta h 2 、h 3 、h 4 、h 5 ..., according to h 2 、h 3 、h 4 、h 5 .., drilling the hole, and under the condition of keeping the included angle between the loading hole and the inclined hole unchanged, constructing the loading hole and the inclined hole again on the same joint to obtain a target area S surrounded by the joint, the loading hole and the inclined hole together 2 、S 3 、S 4 、S 5 ......；
Step S108, repeating the steps S103 to S106 to obtain tau 2 、τ 3 、τ 4 、τ 5 ......；
Step S109, comparing tau, the upper threshold being 1.03 and the lower threshold being 0.92 2 And τ 1 When τ is 2 Not less than the lower threshold value x tau 1 And τ 2 Upper limit threshold value not more than x tau 1 At τ of 2 As the effective value tau of the shearing strength of the structural surface, otherwise, comparing tau 3 And τ 2 .. until an effective value tau of the shear strength of the structural surface is obtained.
6. The in-situ shear strength test method for the structural surface of the surrounding rock of the tunnel according to claim 5, wherein in the step S101, the diameter of the drilled hole is equal to the vertical distance d between the upper structural surface and the lower structural surface.
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