CN110674593A

CN110674593A - Method for automatically predicting over-short excavation in tunnel excavation process

Info

Publication number: CN110674593A
Application number: CN201910953786.1A
Authority: CN
Inventors: 贺鹏; 孙尚渠; 王刚; 郑程程; 姜枫
Original assignee: Shandong University of Science and Technology
Current assignee: Shandong University of Science and Technology
Priority date: 2019-10-09
Filing date: 2019-10-09
Publication date: 2020-01-10

Abstract

The invention discloses a method for automatically predicting over-underexcavation in a tunnel excavation process, which comprises a tunnel rock mass structure surface acquisition system based on a binocular camera system and a tunnel dangerous rock mass batch identification and spatial form distribution prediction system for prediction analysis. The tunnel rock mass plane acquisition system comprises digital image acquisition and structural plane analysis. The tunnel dangerous rock mass batch identification and space form distribution prediction system comprises four plates, namely fracture network model construction, block visual batch search, dangerous rock space form distribution and dangerous rock geometric parameter statistics. The method can be used for realizing the integration of the structural surface acquisition and structural surface analysis methods to guide the design of the tunnel surrounding rock support and the prediction of the over-under-excavation position and the over-under-excavation amount in the tunnel construction process, and the result has practical guiding significance for the field construction and the optimization of the support scheme.

Description

Method for automatically predicting over-short excavation in tunnel excavation process

Technical Field

The invention relates to the field of surrounding rock grading and over under excavation prediction, in particular to an over under excavation automatic prediction method for a tunnel excavation process.

Background

With the continuous development of computer technology, a non-contact acquisition method for acquiring rock mass structural plane information by combining digital photogrammetry with an image processing technology is gradually mature. Joint spreading information such as trace length, dip angle and spacing can be really acquired through a series of image processing and feature extraction algorithms, and development conditions of weak interlayers, fault fracture zones and the like in the range of the engineering rock mass. However, the current structural plane information acquisition method is difficult to meet the current rapid construction requirement of the tunnel, and the overbreak are not easy to control during specific construction. This results in unsatisfactory control effect, and the influence degree of various factors and improvement measures need to be continuously researched to meet the engineering requirements.

Disclosure of Invention

The design mainly aims to overcome the defects in the prior art, and provides a method for automatically predicting the over-short excavation in the tunnel excavation process. The method has the advantages of accurate acquisition, easy operation, clear imaging and improved efficiency when the method is used for the super-under-excavation prediction.

In order to achieve the purpose, the invention adopts the following technical scheme:

the method is used for acquiring information of the rock mass structural plane in the early stage, shooting the same specified area from the left position and the right position, and acquiring the opposite different-view-angle diagram of the same target area; then, on the basis of a camera coordinate reference point calibrated by leveling measurement, adopting a region overlapping concept, and realizing the construction of a rock surface three-dimensional model by means of pixel point matching, three-dimensional coordinate conversion, image synthesis and the like of an overlapped region; and finally, identifying the structural plane by adopting an interactive operation method and a plane fitting method of non-collinear points, realizing the identification and positioning of structural plane individuals and the acquisition of geometric form parameters (attitude, trace length, spacing and the like), and further carrying out statistical analysis on the structural plane attitude. In order to bring the constructed close-range photogrammetry network into a given object measurement network and realize the conversion from two-dimensional image coordinates to three-dimensional geodetic coordinates, the laika TS09plus total station is used for carrying out the geodetic coordinate measurement of the tunnel face control point by combining a redundant observation method of triple repeated collimation based on a tunnel leveling control network by double-disc survey. The tunnel face control points are arranged in a four-corner-point mode, redundant control points are added on the basis of meeting the non-collinear arrangement requirement of the three control points, A, B, C points are used as basic control points, the three-dimensional geodetic coordinates of the model are solved, the redundant control points D are used as the reference, and a distance judgment method is adopted for analyzing the solving precision.

A tunnel dangerous rock mass batch identification and spatial form distribution prediction system for prediction analysis is divided into foreground model construction module design and background dangerous rock spatial distribution module design. The foreground model building module designs a fracture network model which is constructed based on a Monte Carlo algorithm and accords with fracture geometric distribution parameters, because random numbers generated by the Monte Carlo algorithm every time are different, a plurality of fracture network models Xi (i =1,2,3, … n) can be generated by repeating the steps, all fracture groups in different models accord with probability distribution functions, but the overall distribution of the fracture groups in all models is different. The background dangerous rock space distribution module is designed into a fracture network model constructed based on Monte Carlo, geometric search of key blocks in rock bodies around the excavated tunnel is achieved through an unweighted undirected graph breadth search algorithm, and the distribution form and geometric attributes of the key blocks in the space dimension are recorded. The method is used as a simulation cycle, and through the batch simulation of the fracture network model, the search simulation of blocks in the batch simulation model is realized, so that the probability prediction of the space distribution position, size, weight and shape generated by the blocks around the rock mass in the tunnel construction process is realized. The background dangerous stone space spreading module is designed as follows:

1. block search operation procedure

1) Each fracture in FIG. 3 is first numbered, assuming Set { n }₁,n₂,n₃……n_mIn which each one of n is_tIn which two intersection points x are included₁,x₂。

2) Finding all the cracks intersected with the tunnel, and sequencing from near to far according to the distance between the intersection and the leftmost tunnel edge to obtain a Set { e }₁,e₂……,e_m}。

3) From e₁Start the search, search and e₁All intersected cracks and the intersection point o of the crack and the tunnel edge according to the intersection point e1 of the cracks₀The distance of (c) is searched from near to far (breadth) to obtain a fracture Set { p }₁,p₂……,p_m}。

4) And (3) searching whether the set P has the crack of the set E, if so, finding the minimum block (as shown in FIG. 3 (a)), ending the search, returning to the step 3, and if not, continuing the process of the step 3 from 1 in the set P (replacing E1 by P1, continuing the step 3) until the crack in the set E is obtained and the calculation is completed (as shown in FIG. 3 (b)), or the obtaining of an empty set is ended.

5) After all cycles, the blocks were displayed.

2. Block spreading form visual display

After key blocks around the tunnel face are searched in the once-determined joint network simulation model, the geometric shape distribution of each key block, including the central point coordinates, the area, the weight, the shape, the distribution angle relative to the tunnel inverted arch center and the like of the key block, is recorded respectively (see fig. 4). In the simulation of the batch joint network, different dangerous stone communities can be searched in batches (see fig. 5), the geometric information of each key block is recorded according to the above, the probability distribution model of each geometric parameter is constructed, mathematical statistical analysis is carried out, block space distribution rose patterns are synchronously generated, wherein the length of rose petals represents the number of dangerous stones, the width represents the volume of the dangerous stones, and the pointing angle represents the distribution position of the dangerous stones in the rock mass around the tunnel (see fig. 6).

The invention has the beneficial effects that:

(1) the rock mass plane construction information is effectively collected, and the collected data is more accurate;

(2) the method realizes effective prediction of the overbreak and underexcavation, saves cost and reduces errors.

Drawings

FIG. 1 is a flow chart of the binocular stereo camera system of the present invention;

FIG. 2 is a structural plane extraction diagram of the present invention;

FIG. 3 is an application of the breadth first search algorithm of the present invention to key block search;

FIG. 4 is a visual interface of a background dangerous stone space distribution module according to the invention;

FIG. 5 shows the dangerous stone space distribution form searched by the present invention based on different fracture network models;

FIG. 6 is a rose diagram showing the spatial morphology of dangerous stones under different simulation times in batches.

Claims

1. A method for automatically predicting the over-short excavation in the tunnel excavation process is characterized by comprising the following steps of: obtaining structural plane information data and tunnel dangerous rock mass batch identification and space form distribution prediction by digital photography; the digital photography is realized based on a binocular camera system, palm surface area joint and fracture real spread information is obtained through image processing and feature extraction, and the stability of the palm surface area joint and fracture real spread information is primarily judged through surrounding rock grading; the prediction of the over-under excavation position and the over-under excavation amount is realized by network simulation and block search after a rock mass structural plane is obtained, the system is based on a fracture network model constructed by Monte Carlo, realizes geometric search of key blocks in rock masses around an excavated tunnel by using an unweighted undirected breadth search algorithm, and records the distribution form and the geometric attributes of the key blocks in the spatial dimension; through the batch simulation of the fracture network model, the search simulation of blocks in the batch simulation model is realized, and the probability prediction of the space distribution position, size, weight and shape generated by the blocks around the rock body in the tunnel construction process is further realized; the method takes the rock mass fracture network as an unweighted undirected graph, realizes the rapid search and batch identification of the movable blocks in the rock mass around the tunnel based on the breadth-first search algorithm, realizes the visual display of the dangerous rock mass in different rock mass fracture network models on the spatial form, and realizes the prediction of the over-under excavation position and the over-under excavation amount through mathematical statistics.