阅读说明：本技术 一种深埋高压注浆隧洞围岩渗透特性与承载能力测试方法 (Method for testing permeability and bearing capacity of surrounding rock of deep-buried high-pressure grouting tunnel ) 是由 王如宾 阳龙 赵颖 吴瑾 于 2020-06-29 设计创作，主要内容包括：本发明公开了一种深埋高压注浆隧洞围岩渗透特性与承载能力测试方法,该方法基于蒙特卡洛Monte-Carlo模拟深埋高压隧洞裂隙围岩真实损伤裂隙网络；采用裂隙网络逆向重构岩体结构面虚拟模型,3D打印出岩体结构面试样；采用高压涌水注浆堵水对打印出的岩体试样注浆；在全自动三轴力学伺服实验系统中进行注浆裂隙岩体试样的渗透性和承载能力测试。将已进行三轴力学实验的岩体试件进行CT电镜扫描所获得的数据、图像进行比对分析,获得岩体试件内部结构变化规律。本发明通过分析得到注浆裂隙围岩的渗透特性与承载能力,并运用于深埋高压隧洞注浆裂隙围岩工程,检测隧洞开挖注浆裂隙围岩内部结构的稳定性,提高了隧洞开挖施工的安全性。(The invention discloses a method for testing permeability and bearing capacity of a deeply-buried high-pressure grouting tunnel surrounding rock, which simulates a real damage fracture network of a deeply-buried high-pressure tunnel fractured surrounding rock based on Monte-Carlo; reversely reconstructing a rock mass structural plane virtual model by adopting a fracture network, and 3D printing a rock mass structural plane sample; grouting the printed rock mass sample by adopting high-pressure water burst grouting and water plugging; and testing the permeability and the bearing capacity of the grouting fractured rock mass sample in a full-automatic triaxial mechanical servo experiment system. And comparing and analyzing data and images obtained by scanning the rock mass test piece subjected to the triaxial mechanical experiment by using a CT (computed tomography) electron microscope to obtain the change rule of the internal structure of the rock mass test piece. The permeability and the bearing capacity of the grouting fractured surrounding rock are obtained through analysis, the method is applied to deep-buried high-pressure tunnel grouting fractured surrounding rock engineering, the stability of the internal structure of the tunnel excavation grouting fractured surrounding rock is detected, and the safety of tunnel excavation construction is improved.)

1. A method for testing permeability and bearing capacity of surrounding rock of a deeply-buried high-pressure grouting tunnel is characterized by comprising the following steps of: the method comprises the following steps:

(1) simulating a real damage fracture network of the fractured surrounding rock of the deep-buried high-pressure tunnel based on a Monte-Carlo simulation method;

(2) reversely reconstructing a rock mass structural plane virtual model by adopting a fracture network, and 3D printing a rock mass natural structural plane sample;

(3) grouting the printed rock mass sample by adopting a high-pressure water burst grouting and water plugging method;

(4) testing the permeability and the bearing capacity of the grouting fractured rock mass sample in a full-automatic triaxial mechanical servo experiment system, and analyzing to obtain an evolution rule of the internal structure of the rock sample;

(5) and comparing and analyzing data and images obtained by scanning the rock mass test piece subjected to the triaxial mechanical experiment by using a CT electron microscope with the internal mechanism of the test piece before and after the triaxial mechanical experiment, and analyzing and verifying the internal structure change rule of the rock mass test piece.

2. The method for testing the permeability and the bearing capacity of the surrounding rock of the deep-buried high-pressure grouting tunnel according to claim 1, wherein the method comprises the following steps: in the step (1), a Monte Carlo Monte-Carlo simulation method is combined with three-dimensional geotechnical engineering software to measure and group the grouting cracks of the deep-buried high-pressure tunnel, so that a real damage crack network of the surrounding rock of the crack of the deep-buried high-pressure tunnel is simulated.

3. The method for testing the permeability and the bearing capacity of the surrounding rock of the deep-buried high-pressure grouting tunnel according to claim 1, wherein the method comprises the following steps: in the step (2), contour coordinate values are obtained through a Monte Carlo Monte-Carlo method and a fracture network constructed by three-dimensional geotechnical engineering software, and a three-dimensional model is obtained through reverse construction.

4. The method for testing the permeability and the bearing capacity of the surrounding rock of the deep-buried high-pressure grouting tunnel according to claim 1, wherein the method comprises the following steps: in the step (4), when the permeability test of the grouting fractured rock mass sample is carried out in the full-automatic triaxial mechanical servo experiment system, a water saturation test is firstly carried out on the rock test piece, the osmotic pressure is increased on the premise that the confining pressure and the axial pressure are not changed, the water flow of the rock sample permeated by different osmotic pressures in the same time period is obtained, when the water flow of the sample permeated in unit time is not changed, the permeability corresponding to the rock sample in the time period is obtained, and the permeability characteristic of the rock sample is obtained through analysis.

5. The method for testing the permeability and the bearing capacity of the surrounding rock of the deep-buried high-pressure grouting tunnel according to claim 1, wherein the method comprises the following steps: when the bearing capacity of the grouting fractured rock mass sample is tested in the full-automatic triaxial mechanical servo experiment system, the bearing capacity model of the grouting fractured rock mass sample is established by increasing an axial pressure unloading confining pressure compaction experiment and fitting the relation between axial stress strain and lateral stress strain of experiment test pieces with different initial axial pressures.

6. The method for testing the permeability and the bearing capacity of the surrounding rock of the deep-buried high-pressure grouting tunnel according to any one of claims 1 to 5, wherein the method comprises the following steps: the operation steps of the step (5) are as follows:

(51) scanning rock samples with different loads and different loading times, and detecting absorption data of different positions of a test piece on X-rays by using a detector;

(52) after the computer analyzes and calculates, the internal change projection CT image of the rock sample is obtained;

(53) and comparing the images with different loads and different loading times, and analyzing to obtain the change rule of the internal structure of the test piece.

Technical Field

The invention relates to a grouting method for a deep-buried high-pressure tunnel, in particular to a method for testing the permeability and bearing capacity of grouting cracks surrounding rock of the deep-buried high-pressure tunnel.

Background

In the practice of geotechnical engineering, because of complicated geological conditions and large buried depth of a high-pressure tunnel, the phenomena of hole wall collapse and water burst are easy to occur in the construction process, and the bearing capacity of a rock body and the stability of the structure are mostly increased by adopting a grouting technology. However, in terms of the current construction process and technology, the conventional drilling grouting leak stoppage method has high construction difficulty in tunnels, the safety of constructors cannot be guaranteed, the construction progress cannot be guaranteed, and the construction effect is difficult to accurately master.

Disclosure of Invention

The purpose of the invention is as follows: the invention provides a method for testing permeability and bearing capacity of surrounding rock of a deeply-buried high-pressure grouting tunnel, which aims to solve the technical problems that construction in the tunnel is difficult and the construction effect is difficult to accurately master in the prior art.

The technical scheme is as follows: the method for testing the permeability and the bearing capacity of the surrounding rock of the deeply-buried high-pressure grouting tunnel comprises the following steps of:

(1) simulating a real damage fracture network of the fractured surrounding rock of the deep-buried high-pressure tunnel based on Monte-Carlo;

(2) reversely reconstructing a rock mass structural plane virtual model by adopting a fracture network, and 3D printing a rock mass natural structural plane sample;

(3) grouting the printed rock mass sample by adopting a high-pressure water burst grouting and water plugging method;

(4) testing the permeability and the bearing capacity of the grouting fractured rock mass sample in a full-automatic triaxial mechanical servo experiment system;

(5) and comparing and analyzing data and images obtained by scanning the rock mass test piece subjected to the triaxial mechanical experiment by using a CT (computed tomography) nondestructive electron microscope with the internal mechanism of the test piece before and after the triaxial mechanical experiment, and analyzing and verifying the internal structure change rule of the rock mass test piece.

In the step (1), the actual deep-buried high-pressure tunnel grouting fractures are measured and grouped by combining three-dimensional geotechnical engineering software based on a Monte-Carlo simulation method, and a real damage fracture network of the deep-buried high-pressure tunnel fracture surrounding rock is simulated.

In the step (2), reversely reconstructing a rock mass structural plane virtual model, adopting reverse engineering software, obtaining contour coordinate values by using the existing samples through a fracture network constructed by Monte Carlo technology and three-dimensional geotechnical engineering software, and reversely constructing to obtain a three-dimensional model; and then 3D printing out a rock natural structural surface sample, adopting high polymer plastics as a printing material, stacking layer by layer according to the three-dimensional model to form a rock test piece, and obtaining the rock test piece with consistent structural surface appearance in batches.

And (4) performing permeability test on the grouting fractured rock mass sample in a full-automatic triaxial mechanical servo experiment system, performing a water saturation test on each group of rock test pieces, ensuring that the rock sample is in a water saturation state before being placed into an experimental instrument, placing the experimental instrument into the experimental instrument, and sealing the triaxial chamber. Under the premise that confining pressure and axial pressure are not changed, a water passing valve at the upper end of the test piece is opened, osmotic pressure is increased within a set limit range, water flow of rock samples permeated by osmotic pressure of different sizes in the same time period is obtained, and when the water flow of the samples permeated in unit time is stable and unchanged, the rock samples generate stable seepage, so that the permeability corresponding to the rock samples in the time period is obtained. And measuring and analyzing the influence of the damage variable and the permeability obtained by measuring the elastic modulus of the rock sample on the internal structure of the rock sample to obtain the permeability characteristic of the rock sample.

When the bearing capacity of a grouting fractured rock mass sample is tested in a full-automatic triaxial mechanical servo experiment system, the axial pressure unloading confining pressure compaction experiment is added, the relation between the axial stress strain and the lateral stress strain of experiment test pieces with different initial axial pressures is fitted, and a bearing capacity model of the grouting fractured rock mass sample is established.

Because the internal structure of the rock sample can be observed by scanning through the CT electron microscope and the internal structure of the rock sample cannot be damaged in the scanning process, the change rule of the internal structure of the test piece is analyzed and verified according to the comparison of the CT image scanned by the CT electron microscope and the internal mechanism of the test piece before and after the triaxial mechanical experiment.

In the step (5), the data and the image obtained by the CT nondestructive electron microscope scanning of the rock mass test piece subjected to the triaxial mechanical experiment are compared and analyzed, and the specific operation steps are as follows:

(51) scanning rock samples with different loads and different loading times, scanning multiple layers of each test piece, and detecting absorption data of different positions of the test piece on X rays by using a detector of an experimental system;

(52) after the computer analyzes and calculates, the internal change projection CT image of the rock sample is obtained;

(53) and comparing the images with different loads and different loading times, and analyzing to obtain the change rule of the internal structure of the test piece.

The working principle is as follows: the Monte Carlo Monte-Carlo simulation method is a random simulation method based on probability and statistical theory, and it links the probability model with the problem to be solved, and realizes statistical simulation or sampling by electronic computer to obtain approximate solution.

The Monte Carlo Monte-Carlo simulation method is applied to simulation of a grouting fractured surrounding rock network of a deep-buried high-pressure tunnel, and fractured rock samples are printed by combining 3D printing, so that grouting and permeability characteristic and bearing capacity tests are performed in a laboratory, and further the permeability characteristic and later long-time evolution performance rule of the fractured surrounding rock after grouting reinforcement are summarized.

Has the advantages that: compared with the prior art, the invention has the following advantages:

(1) the method provided by the invention combines the Monte Carlo Monte-Carlo simulation technology and the three-dimensional geotechnical engineering software, combines the random simulation calculation method and the three-dimensional modeling method, generates the rock mass sample with the fracture network parameters identical to those of rocks in actual engineering, and improves the accuracy and reliability of the experiment.

(2) The method combining the full-automatic triaxial mechanical servo test and the CT scanning electron microscope provided by the invention uses the CT scanning electron microscope technology to research the internal mechanism of the test piece before and after the triaxial mechanical test, compares the structural changes before and after the stress and strain process of the CT electron microscope scanning test piece, analyzes and obtains the internal structural change rule of the test piece, compares the evolution rules of the internal structure of the rock sample obtained by the rest full-automatic triaxial mechanical servo tests, and mutually verifies the accuracy of the test result and the operability in the actual engineering.

(3) The permeability and the bearing capacity of the grouting fractured surrounding rock are obtained through analysis, the method is applied to deep-buried high-pressure tunnel grouting fractured surrounding rock engineering, the stability of the internal structure of the tunnel excavation grouting fractured surrounding rock is detected, and the safety of tunnel excavation construction is improved.

Drawings

FIG. 1 is a schematic flow diagram of the present invention;

FIG. 2 is a flow chart of Monte Carlo simulation technique;

FIG. 3 is a flow chart of a method for manufacturing a 3D printed rock mass natural structural plane sample.

Detailed Description

As shown in fig. 1 to 3, the method for testing the permeability and the bearing capacity of the surrounding rock of the deeply buried high-pressure grouting tunnel comprises the following steps:

(1) simulating a surrounding rock damage fracture network excavated by the deep-buried high-pressure tunnel by adopting a Monte Carlo Monte-Carlo simulation method, measuring actual fractures, obtaining fracture parameters of an inclination angle, a position, a radius and a gap width, determining the number of groups by adopting three-dimensional rock software, accurately grouping by using statistical analysis software, determining the type of a distribution function, and compiling a program to generate the fracture network;

(2) the rock fracture network constructed based on Monte Carlo Monte-Carlo simulation adopts reverse engineering software, utilizes the existing samples, obtains contour coordinate values through a fracture network constructed by a Monte Carlo method and three-dimensional geotechnical engineering software, and reversely constructs to obtain a three-dimensional model;

(3) adopting high polymer plastics as printing materials, stacking layer by layer according to a three-dimensional model to form rock test pieces, and carrying out 3D printing in batches to obtain the rock test pieces with consistent structural surface appearance;

(4) grouting the manufactured fractured rock sample by a high-pressure water burst grouting and water plugging mode, plugging the orifice by using a grouting hole instrument, reaming the orifice end by using a drill bit with the diameter of 10mm for 20mm after the first time of hole opening is completed, placing the grouting hole instrument in a drilled hole, injecting water by using a manual pressure test water pump, ensuring that the water pressure is 4Mpa, and withdrawing the drill rod after the grouting is completed. Injecting water through a joint grouting pipe and a pipeline in the hole sealing instrument which are made in advance, keeping stable water pressure for 4-5 minutes, unloading the water pressure in the drill hole and the capsule at one time, taking out the hole sealing instrument, installing a single valve at the front end of the pipeline of the hole sealing instrument, and repeating the previous water injection step. Sequentially mixing water and ash in a mass ratio of 1:5, 1:4,1:3, 1: 2,1:1,1:0.5 of cement paste, connecting the pipelines, and respectively injecting the cement paste until the grouting pressure reaches 10 Mpa; closing the connector, dismounting the grouting pipe, cleaning the grouting pump, taking out the hole sealing instrument, and cleaning a pipeline and a single valve in the hole sealing instrument;

(5) adopt full-automatic triaxial mechanics servo experimental system to carry out the test to the infiltration characteristic and the bearing capacity of slip casting crack rock sample, carry out the saturation experiment to each subassembly to put into laboratory glassware with its rock specimen, its concrete experimental procedure is as follows:

(51) under the premise of keeping the confining pressure and the axial pressure unchanged, the magnitude of osmotic pressure is changed, the osmotic pressure grades are divided into 1Mpa,1.5Mpa,2Mpa,2.5Mpa,3Mpa,3.5Mpa and 4Mpa, the loading rate of the osmotic pressure is positioned to be 0.5Mpa/min, in the experimental process, the travel of a water pressure pump is collected once in each unit time of a machine, the water flow permeating the rock sample in the set time is calculated according to the travel, but when the water flow permeating the rock sample in the unit time is stable and unchanged, the stable seepage is generated in the rock sample at the moment, the corresponding permeability of the test piece in the time period can be obtained, and the change rule of the internal structure of the rock sample is analyzed by combining damage variables obtained by measuring the elastic modulus of the rock sample;

(52) the initial axial pressure is respectively 5Mpa,10Mpa,15Mpa,20Mpa,25Mpa,30Mpa and 35Mpa, the initial confining pressure of the corresponding test group is consistent with the initial axial pressure, the loading and unloading time is respectively 5min,7.5min,10min,12.5min,15min,17.5min and 20min, after the uniform axial pressure and the confining pressure reach the target values according to the condition of hydrostatic pressure, the confining pressure is reduced at the unloading rate of 2.5Mpa/min, the axial pressure is increased at the loading rate of 2.5Mpa/min, the axial and lateral stress and strain data of the rock sample are recorded every 1min, and after the experiment is finished, the axial and lateral stress strain relation of the experiment rock sample with different initial axial pressures is fitted;

comprehensively analyzing the experimental analysis result and the mechanical parameters, and establishing a model of the permeability and the bearing capacity of the grouting fractured rock sample;

(6) the method comprises the following specific operation steps of carrying out comparison analysis on data and images obtained by carrying out CT (computed tomography) nondestructive electron microscope scanning on a rock mass test piece subjected to a triaxial mechanical experiment to obtain the change rule of the internal structure of the rock mass test piece:

(61) scanning rock samples with different loads and different loading times, scanning 2000 layers of each test piece, and detecting absorption data of different positions of the test piece on X rays by using a detector of an experimental system;

(62) after the computer analyzes and calculates, the internal change projection CT image of the rock sample is obtained;

(63) and comparing the images with different loads and different loading times, and analyzing to obtain the change rule of the internal structure of the test piece.