Effects of seepage-induced erosion on nonlinear hydraulic properties of broken red sandstones

Velocity model inversion is one of the most important tasks in seismic exploration. Full-waveform inversion (FWI) can obtain the highest resolution in traditional velocity inversion methods...

Deep-learning seismic full-waveform inversion for realistic structural models

The reasons, prevention, and control of loess disaster are of great concern in practice. In recent years, Xi’an city, China, has taken the leadership in large-scale construction of subway lines in the loess strata. To study the structural response of the tunnel in loess region under local hydrodynamic environment, an experimental testing in 1g as well as a numerical simulation were performed, in which the achieved results were verified and were found to be in good agreement. Furthermore, the results showed that when the water outlet point is above the lining, the overall stress of the lining is “peanut shell,” as the water pressure of the outlet point decreases, the tensile stress of the top and bottom of the lining increases, while the compressive stress on both sides decreases; the channel form of the flow to the lining changes with the variation of the position of the water outlet point. It is worth mentioning that in the process of water gushing, the closer to the water source, the greater surface subsidence is, and there is a positive correlation between water pressure and surface subsidence. This study is of significant benchmark for the construction, maintenance, and prevention of tunnel in loess strata under the influence of water environment.

Structural Response of the Metro Tunnel under Local Dynamic Water Environment in Loess Strata

Study on an improved real-time monitoring and fusion prewarning method for water inrush in tunnels

3D scene and geological modeling using integrated multi-source spatial data: Methodology, challenges, and suggestions

4-D electrical resistivity tomography (ERT), an important geophysical method, is widely used to observe dynamic processes within static subsurface structures. However, because data acquisition and inversion consume large amounts of time, rapid changes that occur in the medium during a single acquisition cycle are difficult to detect in a timely manner via 4-D inversion. To address this issue, a scheme is proposed in this paper for restructuring continuously measured data sets and performing GPU-parallelized inversion. In this scheme, multiple reference time points are selected in an acquisition cycle, which allows all of the acquired data to be sequentially utilized in a 4-D inversion. In addition, the response of the 4-D inversion to changes in the medium has been enhanced by increasing the weight of new data being added dynamically to the inversion process. To improve the reliability of the inversion, our scheme uses actively varied time-regularization coefficients, which are adjusted according to the range of the changes in model resistivity; this range is predicted by taking the ratio between the independent inversion of the current data set and historical 4-D inversion model. Numerical simulations and experiments show that this new 4-D inversion method is able to locate and depict rapid changes in medium resistivity with a high level of accuracy.

A rapid four-dimensional resistivity data inversion method using temporal segmentation

An improved Time-Lapse resistivity tomography to monitor and estimate the impact on the groundwater system induced by tunnel excavation

The invention discloses a comprehensive boulder detection model test device suitable for a plurality of earth physical detection methods, and a test method thereof The device comprises a boulder burying area arranged on the upper part of a substrate rock stratum, and a plurality of boulders or boulder groups are arranged in the boulder burying area The device further comprises a plurality of boreholes penetrating through the boulder burying area to the bottom surface of the substrate rock stratum Electrodes are arranged in the boreholes The electrodes are connected with a host capable of applying a spatial point source electric field so as to realize the detection of cross-hole resistivity CT method A seismic source is arranged in one borehole, a detector is arranged in one borehole, and the detector is connected with the seismic source host for collecting signals so as to realize the detection of a seismic wave CT method The comprehensive boulder detection model test device and the test method have the advantages that the test research of the boulders by the plurality of physical detection methods can be performed by the arranged boreholes, the electrodes arranged on the surface of plain fill and an observation system of a triangular array type, and a relatively ideal detection test platform is provided for the engineering boulder detection problem

Comprehensive boulder detection model test device suitable for plurality of earth physical detection methods, and test method thereof

The invention discloses an advanced three-dimensional electrical resistivity cross-hole computed tomography (CT) solitary stone detection system carried by a shield tunneling machine and a detection method. The system comprises an advanced drilling device capable of drilling at least four drill holes in the rock surface. The multiple drill holes form a three-dimensional detection space. The advanced drilling device comprises a drilling machine. The bottom of the drilling machine is movably fixed to a rail on the inner circumference of a shield. A drill bit of the drilling machine penetrates through an advanced grouting hole of the shield. The system further comprises a detection electrode coupling device which stretches into the drill holes, is provided with a plurality of electrodes, and is capable of releasing electrolytes to the electrodes. The detection electrode coupling device is connected with a host machine used for applying a three-dimensional space electric field through a cable. The advanced three-dimensional electrical resistivity cross-hole CT solitary stone detection system carried by the shield tunneling machine and the detection method have the beneficial effects that the defects that holes cannot be drilled in a cutter head of the shield tunneling machine, or a drilling device cannot be installed on a tunnel face are effectively overcome; the advanced drilling device is installed in the shield of the shield tunneling machine, and advanced drilling is achieved through the advanced grouting hole in the shield of the shield tunneling machine; and difficulty in the prior art is overcome, and simplicity and convenience are achieved.

Advanced three-dimensional electrical resistivity cross-hole computed tomography (CT) solitary stone detection system carried by shield tunneling machine and detection method

The invention discloses a pseudo-random frequency-sweeping nuclear magnetic resonance detection instrument. The instrument comprises a control and communication module, a pulse transmitting module, a response signal receiving module, a frequency sweeping control module and a pulse frequency modulation module, wherein the response signal receiving module acquires nuclear magnetic resonance response signals excited by pseudo-random frequency-sweeping nuclear magnetic resonance excitation pulses and transits the nuclear magnetic resonance response signals to the control and communication module; and the control and communication module calculates the frequency deviation degree between the current excitation frequency and the actual Larmor frequency according to the features of the nuclear magnetic resonance response signals so as to judge whether the received response signals are the optimal response signals or not. The instrument disclosed by the invention can transmit pseudo-random frequency-sweeping nuclear magnetic resonance excitation pulses so as to excite nuclear magnetic resonance responses on multiple frequency points.

Xinxin Zhang

Papers

A rapid four-dimensional resistivity data inversion method using temporal segmentation

An improved Time-Lapse resistivity tomography to monitor and estimate the impact on the groundwater system induced by tunnel excavation

Comprehensive boulder detection model test device suitable for plurality of earth physical detection methods, and test method thereof

Advanced three-dimensional electrical resistivity cross-hole computed tomography (CT) solitary stone detection system carried by shield tunneling machine and detection method

Pseudo-random frequency-sweeping nuclear magnetic resonance detection instrument