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The study developed a two-level Bayesian framework to account for site specific variability in bias estimates for pile capacity evaluations using cone penetration test (CPT) data. The framework updated a weak prior for the bias factor with regional data in level 1 and with site specific data in level 2. A confidence bias site parameter was introduced to give more weight to site specific data. The framework improved existing methods by combining regional data, site specific data, and engineering judgement. The proposed approach was applied to assess the bias factors for pile capacity at three sites in Louisiana: Houma Bridge, Gibson Highway and Causeway Boulevard. The resulting bias factors were used to estimate the site-specific resistance factors for LRFD based design, which are typically calibrated using statewide or nationwide data. The results highlight that the selection of prior data in level 1 Bayesian analysis has little effect on the updated posterior data of specific site. In general, the updated posterior parameters for the specific new site lie between the prior2 parameters and the likelihood2 parameters, taking into consideration the specific site variability. Posterior2 data can be used to determine the LRFD resistance factor ( $${\upphi }_{R}$$ ) for the design of piles based on pile-CPT design methods for the specific site. More weight should be given to new pile load test data using the confidence bias site parameter, which depends on the site condition and extent of testing.

Large deformation disasters of tunnels greatly affect the construction time and quality of the tunnel. In order to best reduce the impact of large deformation disasters on tunnel construction and prevent the problems before they occur, this paper had proposed a method of large deformation disaster prediction and grading technology for deep buried tunnels with high stress, which mainly depends on stress inversion; this model was applied to predict the location and severity of the large deformation disasters of Anding tunnel. Lastly, the accuracy and characteristics of the prediction results were judged using the statistical data of large deformation disasters that occurred during the tunnel construction process. The results show that the errors between stress inversion and borehole measured data were basically within 25%; thus, it is feasible to obtain the in situ stress distribution characteristics of the tunnel by means of stress inversion. The large deformation disaster prediction method proposed in this paper had an accuracy of 62.5% in predicting the location of large deformation disasters, achieving good results in this respect; hence, it can play a very important role in further prevention and control of large deformation disasters.

TBM tunnelling is less used in the subway construction in prosperous city due to the limitation of the engineering geological conditions. The studies on the influence of the TBM construction on the existing buildings are also limited. Therefore, based on the engineering case of tunnel crossing existing building in the section of Haiboqiao ~ Xiaocunzhuang station of Qingdao Metro Line 1, the numerical model that simulates the construction process of TBM tunnelling in slightly weathered granite layer is established by three-dimensional finite difference software FLAC3D to analyze the influence of TBM tunnelling. The comparisons between ground deformations obtained by FLAC3D and field monitoring data in different construction stages of double-line tunnel have been made firstly to validate the numerical model. Then the ground settlement characteristics, differential settlement and the stress distribution of the existing building and the stress of segment structure have been analyzed. During TBM tunnelling under existing building, the settlement of the building as a whole tends to increase, with the maximum measured settlement of 5.45 mm and the maximum differential settlement of 1.58 mm, which meets the control standard of relevant codes. Ground settlement groove along the transverse and vertical sections occurs near the building and tunnels, and the settlement becomes smaller with the farther the distance from the building and tunnels. The settlement curve on the cross section changes dynamically and is approximately V-shaped, and its width is about 5 ~ 6 times diameter of the tunnel. For the same cross section, the range of the settlement groove after tunnelling right line increases obviously compared with that after tunnelling left line (first construction), the settlement values also increase, and the symmetrical axis of the settlement curve is shifted to the right. For the segment structure, the maximum principal tensile stress occurs inside the arch bottom of the tunnel, while the maximum principal compressive stress occurs near the arch top and arch waist, with obvious stress concentration. For the existing building, the maximum principle tensile stress occurs at the door opening of the wall on the first floor and the maximum principal compressive stress is at the corner of wall. They are less than the tensile strength and compressive strength of the segment structure and building respectively, and have enough safety margins. This paper can provide important practical reference for the deformation control and protection design of surrounding buildings for relative construction.

In western China, red sandstone is widely distributed. This type of rock is susceptible to generate cracks after being disturbed, and thus becomes a communication channel for groundwater, which poses a great hidden danger in Engineering, such as shaft and tunnel construction. To solve this problem, artificial freezing method is applied to underground engineering. This article focuses on the dynamic tensile strength of red sandstone (RS) at negative temperatures. According to the actual freezing temperature in the site, the temperature range was set to − 5, − 10, − 20 °C in the test, and the rock at normal temperature was set as a control group. The results show that the tensile strength of RS at temperatures below zero is significantly greater than the tensile strength of rock at normal temperature, and − 10 °C is a turning point of rock strength. In order to reveal the mechanism of this change, the scanning electron microscopic (SEM) technique was used to observe the rock fragments after the rock rupture. It is found that the rock fracture patterns are closely related to the rock cement property and its environmental temperature.

The effect of the spring mounting cushion inserted in between a machine base and its concrete footing has been examined experimentally by conducting a number of block vibrations tests. The machine was subjected to steady state vertical harmonic loading. Experiments were performed with two different stiffness values of the spring mounting cushion. The employment of the spring mounting cushion, with the stiffness much smaller than that of soil strata, offers a drastic reduction in the resonant displacement amplitudes of the footing. It also results in a significant decrease in the resonant frequency of the foundation. The resonant displacement amplitudes of both the footing and the machine were found to become lower with the smaller stiffness value of the springs. The resonant frequency for the machine base, in all the experiments, was found to be invariably the same as that of the footing.

Water inrush due to fault activation in deep coal mining is the main type of water disaster in central and eastern China. This paper analyzed the primary form and mechanism of fault activation that triggers water inrush and derived the critical conditions for fault activation. The WuGou coal mine is used as a geological example, and the characteristics of the fault activation and mechanism of the confined water rising were researched by similar simulation experiments. The results provide the following conclusions. (1) There are three forms of fault activation that trigger water inrush: continuous fault, hidden fault and associated fault activation. (2) Mining causes high abutment pressure in a coal seam; this pressure transfers to the floor, causing damage and failure. The maximum failure depth occurs when the overlying strata is in a critical fractured state. The cracks of the floor gradually close in the goaf. (3) The fault activation causes water inrush and exhibits four stages: fault zone yielding caused by high stress, cracking and extending of the fault zone, movement and slippage of the fault zone, and confined water rising. (4) The influence factors of the confined water rising were analyzed. The experimental results show a negative correlation between the confined water height and distance to the fault zone and a positive correlation among the confined water pressure, fault zone width and confined water height. In addition, a strong–weak–strong change law of the confined water pressure with height is observed.

Two-dimensional plane strain finite element analysis has been used to simulate the inclined pullout behavior of strip anchors embedded in cohesive soil. Previous studies by other researchers were mainly concerned with plate anchors subjected to loads perpendicular to their longest axis and applied through the centre of mass. This paper investigates the behavior of vertical anchors subjected to pullout forces applied at various inclinations with respect to the longest anchor axis, and applied at the anchor top and through the centre of mass. The effects on the pullout behavior of embedment depth, overburden pressure, soil–anchor interface strength, anchor thickness, rate of clay strength increase, anchor inclination, load inclination and soil disturbance due to anchor installation were all studied. Anchor capacity is shown to increase with load inclination angle for anchors loaded through the centre of mass; greater effects are found for higher embedments. The results also show that anchor capacity improves at a decreasing rate with higher rates of increase of soil shear strength with depth. In addition, the capacity of vertically loaded anchors is shown to approximately double when the soil–anchor interface condition changes from fully separated to fully bonded. Similarly, disturbed clay strengths adjacent to the anchor following installation cause a significant reduction in anchor capacity. The results showed a significant effect of the point of load application for anchors inclined and normally loaded. The effects of other parameters, such as anchor thickness, were found to be less significant.

Based uniaxial compression tests of altered granite, the weakening laws of rock strength and energy mechanism of rock failure for altered granite subjected to wet–dry cycles are analyzed. Results show that: (1) with increasing number of wet–dry cycles, the rock weakening coefficient and damage variables increase gradually. The maximum weakening coefficient of altered granite-1 was 50.22%, and the damage variable was up to 63.84%. The maximum weakening coefficient of altered granite-2 was 43.22%, and the damage variable was up to 44.00%. (2) The total energy of rock increases gradually with the number of wet–dry cycles. Elastic strain energy in the rock increases first then decreases. The energy storage limit decreases gradually, showing a linear or exponential relationship with the number of wet–dry cycles. (3) The rock damage energy mechanism under wet–dry cycles is obtained via the rock dissipation energy. The rock dissipation energy increases gradually as the number of wet–dry cycles increases. Wet–dry cycles causes irreversible damage to the rock internal structure.

Crack coalescence in rock masses was studied by performing a series of biaxial compresion tests on specimens made of rock-like material. Specimens of size 63.5 × 27.9 × 20.3 cm, made of 72% silica sand, 16% cement (Type I) and 12% water by weight were tested. The joint inclination angle was maintained at 45°, while the offset angle i.e. angle between the plane of the joint and the line that connects the two inner tips of the joints, was changed from 0° to 90° with an increment of 15°. Three levels of lateral stress were used; 0.35 MPa, 0.7 MPa and 1.5 MPa on each sample. HP data acquisition system was used to record the data for each sample. In each sample, four LVDTs were fixed to measure the axial and lateral displacement along the sample. The failure mechanisms were monitored by eye inspection and a magnifier to detect crack initiation and propagation. For each test, the failure surfaces were investigated to determine the characteristics of each surface. Wing cracks initiated at the tip of the joint for the low confining stress applied, while at higher confining stresses wing cracks also initiated at the middle of the joint. Secondary cracks initiated at the tip of the joint due to shear stress. Three modes of failure took place due to coalescence of the secondary and wing cracks. The bridge inclination was the main variable that controlled the mode of failure. For bridge inclination of 0°, the coalescence occured due to shear failure and for bridge inclination of 90° the coalescence occurred due to tensile failure while for the other bridge inclinations coalescence occured due to mixed tensile and shear failure.

Hệ số đàn hồi là một trong những tham số quan trọng nhất trong mô hình hóa quỹ đạo rơi đá. Tuy nhiên, chúng rất khó thu thập, phụ thuộc vào nhiều tham số, và biến thiên đáng kể ngay cả trong các điều kiện địa kỹ thuật và động học tương tự. Nhiều định nghĩa về hệ số đàn hồi đã được đưa ra, nhưng không có sự đồng thuận về định nghĩa nào tốt hơn trong việc mô tả phản ứng của một khối khi va chạm. Trong bài viết này, một nghiên cứu thực nghiệm mở rộng được trình bày, bao gồm 600 thí nghiệm tác động xiên và các định nghĩa khác nhau về hệ số đàn hồi được đánh giá, với sự nhấn mạnh vào ảnh hưởng của góc va chạm và tốc độ góc. Các thí nghiệm này theo sau nghiên cứu được trình bày trong Asteriou và Tsiambaos (Int J Rock Mech Min Sci 106:41–50, 2018), nơi các thử nghiệm rơi tự do được thực hiện nhằm xác định ảnh hưởng của tốc độ va chạm, khối lượng khối đá và loại vật liệu. Kết quả cho thấy tất cả các tham số này có ảnh hưởng đáng kể đến hệ số đàn hồi. Hơn nữa, một mô hình thực nghiệm được đề xuất để ước lượng hệ số đàn hồi cho các va chạm trung tâm. Tính khả thi của mô hình này được mở rộng cho các va chạm xiên dựa trên kết quả của các thí nghiệm được trình bày trong bài viết này.