Simulation and On-Site Detection of the Failure Characteristics of Overlying Strata under the Mining Disturbance of Coal Seams with Thin Bedrock and Thick Alluvium.

When mining deep coal seams with thin bedrock and thick alluvium, the collapse and fracture of thin bedrock layers may cause geological disasters, such as water inrush and sand inrush of the mining face. Comprehensively obtaining the response data of coal mining and reasonably analyzing the failure characteristics of overlying strata are helpful in guiding safe production. In this study, the caving zone heights of overlying strata are obtained by field detection during layered mining. Then, the caving zone heights during the once-full-height mining are evaluated by theoretical analysis. Further, the force and failure characteristics of coal-rock structures under different mining conditions are compared by the simulation detection and analysis. Finally, the results of on-site observation, theoretical analysis, and simulation detection are compared and discussed, and an optimized mining technology is proposed to ensure safe mining. The research shows the caving zone heights of on-site and simulation detections are, respectively, 14.65 m and 13.5 m during bottom-layer mining, which is larger than the caving zone heights of the top-layer coal mining. During once-full-height mining, the maximum caving zone height of simulation detection is 21 m, which is in between two standard results. For the mechanical responses of an aquiclude clay layer under thick loose alluvium, the maximum disturbance displacement of clay aquiclude is 5.8 m during layered mining, which is slightly larger than the disturbance displacement of once full-height mining; however, the maximum stress of the clay layer is 25 MPa during once-full-height mining, which is larger than the maximum stress of clay layer during layered mining. For the clay aquiclude failure, the clay layer during layered mining is in the deflection deformation area, and there is no obvious fracture structure to inrush the water and sand of thick loose alluvium; however, the clay layer during once-full-height mining is prone to produce obvious fracture structure. Therefore, the layered mining technology can effectively reduce and prevent the water/sand inrush disaster of mining working face.

The association between childhood trauma and pain symptoms in depressed adults: The moderating role of anxious attachment.

Studies have previously demonstrated that anxious attachment shapes the association between childhood traumatic experiences and somatic pain; however, it remains unclear how this relationship is influenced by anxious attachment in patients with depression. This study investigated how anxious attachment influences the relationship between childhood traumatic experiences and pain symptoms in depressed patients from a social psychological perspective. A total of 139 adult patients with depression participated in this study; the level of depression was assessed by a psychiatric professional. Childhood trauma, pain symptoms, and attachment dimensions were tested by various questionnaires. The moderating role of anxious attachment in the trauma-pain association was examined using the PROCESS Model 1. Our findings showed that in depressed patients, childhood maltreatment had a significant positive impact on the severity of pain ratings. Moreover, anxious attachment influenced the relationship between childhood trauma and pain symptoms. Our study indicated that anxious attachment is not necessarily a negative outcome for depressed patients; moderate levels of anxious attachment alleviate childhood trauma-related pain symptoms in individuals with highly traumatic experiences. Understanding the traumatic experiences and attachment styles of depressed patients with pain complaints can help to develop intervention strategies.

The Chinese version of the Memory for Intentions Test (MIST): Development and evaluation of its reliability and concurrent validity.

This study aims to develop a simplified Chinese version of the "Memory for Intentions Test" (MIST), evaluate its reliability and concurrent validity, explore the inter-relationships among the MIST variables and the relationships between the MIST variables and socio-demographic factors.Two hundred healthy, Chinese-speaking adults of the Han community participated in this study. Form A of the Chinese MIST and two prospective items of the Rivermead Behavioural Memory Test, Second Edition (RBMT-II, Chinese version) were administered to all participants to evaluate internal consistency, split-half reliability, and concurrent validity. Twenty of these participants were assessed twice on Form A with a two-week interval to examine test-retest reliability. They were also assessed on both Form A and Form B to examine alternate-form reliability.The findings of the study indicated good internal consistency (Cronbach's α = .833) and excellent split-half reliability (r = .924-.930) among the six subscales of the Chinese MIST, although the internal consistency was low (Cronbach's α = .129) for individual PM trials. We also found adequate concurrent validity (ρ = .722, p< .001), test-retest reliability (ρ = .716, p < .001), and alternate-form reliability (ρ= .828, p < .001).The Chinese MIST demonstrated suitable reliability and concurrent validity in the Chinese-speaking population. The present study provides a new standardized prospective memory test for the Chinese population, which would enhance future clinical research in this field on the Chinese mainland.

Investigation of the Fracture Characteristics of a Cement Mortar Slab under Impact Loading Based on the CDEM.

For brittle and quasi-brittle materials such as rock and concrete, the impact-resistance characteristics of the corresponding engineering structures are key to successful application under complex service environments. Modeling of concrete-like slab fractures under impact loading is helpful to analyze the failure mechanism of an engineering structure. In this paper, simulation models of impact tests of a cement mortar slab were developed, and a continuum-discontinuum element method (CDEM) was used for dynamic analysis. Concretely, the cracking simulations of a mortar slab when considering the hammer shape and impact velocity were conducted, and the impact process and failure results of the slab structure were analyzed. The results showed that the top fracture area of the mortar slab was significantly smaller than that of slab bottom under impact loadings of the drop hammer. The impact velocity was an important factor that affected the mortar slab's cracking. With the increase in the initial impact velocity, the effective fracture area of the slab structure increased significantly; the impact force and rupture degree of the mortar slab also showed a linear growth trend. The shapes of the impact hammerhead also had a significant effect on the crack model of the mortar slab. The effective fracture zones of slab structures were close under circular and square hammers, while the effective fracture zone was significantly larger under a rectangular hammer impact. The peak value (45.5 KN) of the impact force under a circular hammer was significantly smaller than the peak value (48.7 KN) of the impact force under the rectangular hammer. When considering the influence of the stress concentration of the impact hammerhead, the maximum impact stress of the rectangular hammer was 147.3 MPa, which was significantly greater than that of the circular hammer impact (maximum stress of 87.5 MPa). This may have meant that the slab structures were prone to a directional rupture that mainly propagated along the long axis of the rectangular hammerhead. This impact mode is therefore more suitable for rehabilitation and reconstruction projects of slab structures.