The main causes of damage include poor site selection, such as building on fault lines or on fill soil, as well as deficiencies in design, materials, and workmanship. Damage levels are also linked to the economic conditions of the region. In the 1939 earthquake, there were high casualties due to the magnitude of the earthquake, lack of engineering design in traditional structures and unsuitable soil conditions. Similarly, in the 1992 earthquake, unexpected damage occurred due to faulty designs created by inexperienced engineers who lacked sufficient knowledge of the seismic behavior of structures, errors in craftsmanship and workmanship, and unsuitable residential area selection for construction. These problems continue today and put most of the building stock at risk in case of a major earthquake. Seismic steel isolators are used in two new buildings in the city; if they are effective, they should be made mandatory in new construction. Otherwise, consideration should be given to relocating the city to the more stable southern rocky areas, which were unaffected in both 1939 and 1992.

The distribution range of soil-rock mixtures (S-RM) in fault zones is wide, with significant differences in mechanical properties, making them the main sites for rock instability and support structure failure in mines. This paper takes the Sanshan Island fault zone as the engineering background, and uses a self-designed small-scale test device to conduct triaxial compression tests to study the strength and deformation failure laws of S-RMs with different rock block proportions (20%, 40%, 60%, and 80%). Combined with numerical simulation test results, the spatial transport laws and microscopic deformation failure characteristics of particles with different particle sizes in the S-RM are revealed. The main conclusions drawn are as follows: (1) For S-RMs with rock block proportions (RBP) of 20%, 40%, and 60%, there is a linear positive correlation between confining pressure and peak strength. When the RBP increases to 80%, there is a non-linear positive correlation between the confining pressure and peak strength of the S-RM sample. Under the same increase in confining pressure, the increase in peak strength of the sample decreases. The influence of confining pressure on the strength and deformation characteristics of S-RMs with high RBP is reduced. (2) During the process of increasing the RBP from 20 to 60%, there is a linear positive correlation between the RBP and peak strength of the S-RM sample. When the RBP increases to 80%, the peak strength of the sample experiences a sudden increase, with an increase of nearly 80 kPa in peak strength. When the RBP is high, the S-RM sample exhibits the mechanical properties of block rocks. (3) The cohesion and internal friction angle of the S-RM sample are positively correlated with the RBP. During the process of increasing the RBP from 20 to 80%, the cohesion increases from 83.12 kPa to 119.38 kPa, and the friction angle increases from 6 degrees to 11 degrees. (4) When the RBP is low (20% and 40%), as the experiment progresses, a significant conjugate shear deformation zone will form within the S-RM sample, and block rock particles will migrate towards this area and undergo shear slip failure between particles. When the RBP is high (60% and 80%), splitting failure mainly occurs at the bonding surface between block rock particles and soil particles inside the sample, and the contact force between particles is relatively large. The relevant research results have important social and economic value for revealing the fracture failure laws of rock masses in fault zones and ensuring the safe development of human engineering activities.

The fault zone represents one of the unfavorable geological conditions responsible for tunnel collapse in undersea tunnels. To reveal the collapse mechanism of an undersea tunnel triggered by the fault zone during excavation, a large-scale tunnel disaster model system was developed, capable of true triaxial loading and providing a sufficient supply of high-pressure water. A hydro-solid coupling similar model test was performed based on the engineering background of the under-construction second Jiaozhou Bay undersea tunnel. The results show that subsea tunnel fault collapse had an obvious progressive nature under excavation disturbance and seawater seepage. Soil arches repeatedly formed and moved upward during the collapse evolution process. When the overburden thickness was insufficient to form a soil arch, the tunnel collapse evolved into a water inrush. In addition, the multi-physics field changed obviously before the collapse, which could be used as precursor information for tunnel instability. Before the collapse, the horizontal stress rose slowly and then dropped suddenly, the pore water pressure drastically fluctuated and peaked, and the loosened zone's displacement rate increased suddenly. This study provided improved insight into the failure behavior of subsea tunnels and identified early warning signs of collapse.

The February 6, 2023 Kahramanmaras,-T & uuml;rkiye ,-T & uuml;rkiye earthquakes with moment magnitudes 7.7 and 7.6 resulted in substantial casualties, injuries and extensive infrastructure devastation. Soil liquefaction was identified as one of the contributing factors to the damages. In this study, a data-driven approach to assess liquefaction-prone areas within an artificial neural network (MultiLayer Perceptron- MLP) was proposed. The study area, selected to cover a region with the size of 11,500 km2 2 containing Amik and Kahramanmaras, , Plains, is governed mainly by active tectonism of the East Anatolian Fault Zone. The earthquakes were considered to be responsible for numerous liquefaction occurrences in both plains. Here, a comprehensive inventory of liquefied regions was compiled from aerial photogrammetric images taken in the days following the earthquakes. Considering the availability of suitable geospatial datasets, the key factors for liquefaction modeling were selected as distance to streams, land use and land cover, slope, and topographic wetness index, and normalized difference water index (NDWI) and normalized difference vegetation index (NDVI) derived from satellite images taken a few days before the earthquakes. The Holocene unit was used as a mask to perform modeling and prediction within this litho- logical type. The F1-score and overall accuracy values obtained from the MLP on a test dataset were 80% and 82%, respectively. The study showed that geospatial databases including airborne and satellite image products have great potential for assessing liquefaction hazard at regional scale, which can be used as base data for planning and conducting further field and laboratory studies to improve the accuracy in predictions.

Loess is a typical structural soil with properties such as water sensitivity, collapsibility, and seismic vulnerability. The dynamic response of a water transmission pipe crossing a fault zone is highly complex in a loess site. The Hanjiang River to the Weihe River Diversion Project (Phase II) crossing the Weihe fault was selected as the prototype for a shaking table test, through which the responses of acceleration, dynamic stresses, strains, and pore-water pressure were systematically investigated. The acceleration response of a geologic body similar to the experimental model was greatly affected by factors such as fault location, degree of soil saturation, distribution of internal structure, and so on. The acceleration along elevation experienced its highest amplification factor of approximately 2.0, mainly due to seismic waves with frequencies above 2.0 Hz being amplified. To ensure the seismic fortification of the pipeline near the fault belt, it is recommended to utilize an acceleration of 1.2 times within the severe impact zone. This zone involved 36.0 m of the hanging wall and 30.0 m of the footwall, which are approximately 6.0 times and 5.0 times of the fault belt width. It is recommended to use an acceleration of 1.1 times for areas within 200 m from the fault of the hanging wall; refer to the fault-avoiding distance of the seismic design code. The deformation mode of the water pipeline was expansion/shrinkage in the transverse and slight bending in the longitudinal section. The pore-water pressure response demonstrated coupling features of hysteresis, accumulation, and dissipation. The seismic collapsibility modes of the loess at the studied site were generalized into four stages: energy accumulation, state mutation, failure extension, and successive failure. Seismic subsidence could be expressed by adopting a piecewise function with a maximum value of approximately 18.0 cm. Based on the similarity calculation, the maximum seismic subsidence of the prototype can be recommended as 3.6 m. Liquefaction occurred when the input acceleration amplitude reached 0.5g. These shaking table test results provided reasonable parameters for the seismic design and construction of the Hanjiang to Weihe River Diversion Project across this fault.