Project overview：

The northwest section of the first phase of Hangzhou metro line 2 starts from Qianjiang road station (excluding) and ends at Fengtan road station, which is 11.84km-total, with 11 shield intervals. The southeast section of the first phase of Hangzhou metro line 2 starts from Shushan depot and ends at Qianjiang road station, which is 18.338km-total, with 13 shield intervals. This project is required to measure the diameter of the ring plate to obtain the geometric size deformation of the ring plate and surface damage, which is used to provide reference for the maintenance of subway operation.

System introduction：

The detection equipment used in this project is GRP5000 tunnel measurement system, which is composed of rail measurement trolley, high-precision scanner, three-defense industrial laptop and high-precision inertial navigation (optional). It is a laser holographic imaging system with optical、mechanical and electrical technologies developed by Swiss Amberg technology company. It is mainly used for detection of tunnel surface state、structural deformation and tunnel clearance during construction、completion acceptance and operation of underground projects.

                                                                   GRP5000

Project implementation：

Line 2 is an operational line, and the window period is generally from 1 AM to 4 AM. The scanning speed on site is 1.5km per hour. After the data collection is completed, post-processing software is used to analyze and process the data, and technical results will be formed. The project flow chart is as follows:

Project flow

Project achievement：

This project processed the collected data through Amberg Rail——the post-processing software of GRP5000 system, to obtain the results of tunnel surface map and cross-section diagram. Next we imported the greyscale image into TunnelMap to label the various facilities and the tunnel surface defect (such as cracks, leakage, etc.). Last cross-section was imported into AR post-processing software to analyze the deformation of tunnel cross-section.

1、 Achievement of Amberg Rail

                                                      Tunnel surface image

                                          Tunnel cross-section

2、Achievement of AR post-processing software

                                                         Fitting ellipse

                                          Ovality analysis table

                        Transverse diameter histogram

3、Achievement of TunnelMap

               Tunnel check statistics sheet

Tunnel damage distribution map

Project conclusion：

We completed 3D laser scanning work of shield intervals in the southeast and northwest sections of the first phase of Hangzhou metro line 2 project, and obtained the appearance state and geometric deformation size of each ring pipe segment, which can serve as a reference for tunnel operation and management of this line. Through data analysis and comparison, it can be proved that 3D laser scanning has good accuracy. The high-definition images can be used for the judgement of tunnel seepage, damage and other appearance diseases, and can be used as the basis for tunnel completion acceptance and status evaluation. Its good repeatability can be used for tunnel stability detection.

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