Weathering mechanism of the Cretaceous argillaceous siltstone caverns,Longyou, China

The Longyou caverns in the Zhejiang province of China were hand dug more than two thousand years ago. Five of these caverns were drained in 1992 and are now a major tourist attraction. Brick red argillaceous siltstones locally mingled with greyish-white flecks are present in the geological sequence in which these caverns have been created. Stress cracks have developed in the roof, walls and pillars and the cavern faces are showing distinct signs of powdering. The paper discusses the nature of the rocks, highlighting the smectititic clay which causes disintegration in the argillaceous siltstones. In addition, in the greyish-white speckled material, dissolution of the calcareous cement results in unbound grains forming on the rock face. The rate of disintegration due to weathering is most pronounced near the openings of the caverns where the effects of the external atmosphere are most marked.      

Design,construction and mechanical behavior of relics of complete large Longyou rock caverns carved in argillaceous siltstone ground

This paper presents a comprehensive summary of data, analyses and findings from the investigations over the past twelve years about the relics of large Longyou rock caverns carved about 2 000 years ago at shallow depths in argillaceous siltstone. The paper presents the typical features associated with the rock caverns. They include structures, large spans, portals, extreme shallow-buried depths, imprints, drainages, inclined ceiling, inclined sidewalls, slender rock pillars, rock staircases, site and strata...     

Engineering geological characteristics,failure modes and protective measures of Longyou rock caverns of 2000 years old

The Longyou rock caverns are a group of large ancient underground caverns. They were caved manually in pelitic siltstone in the Quxian Formation of Upper Cretaceous. They have the following five characteristics: more than 2000 years old, man-caved, large spanned, near ground surface and medium to hard surrounding rock. They were unearthed by local farmers who were pumping water out of five small pools on a rough-flat ground in 1992. This discovery called the attention of many specialists from China, Japan, Poland, Singapore and USA. One of the most interesting and challenging questions is why the five caverns have been able to keep their integrity for more than 2000 years. To address this question, this paper presents the engineering geological conditions of the caverns and their adjacent areas. They include the following five conditions: (a) geological setting, (b) hydrogeological conditions, (c) seepage in integrity caverns, (d) fractures in integrity caverns and (e) failed caverns. Based on these investigation results, the paper further examines the potential failures of the integrity caverns and their protective measures.     

A general model for the calculation of daylighting in interior spaces

An analytical model and a computer code have been developed which calculate the amount of daylight illumination on a working surface inside an arbitrary room, for overcast as well as for clear sky conditions. The room may have windows as well as skylights, with clear glass, diffusing glass, or glass fitted with thin shading devices (such as sheer curtains or shades), as well as overhangs. The shape of the room is not limited to simple, rectangular enclosures, allowing the treatment of L-shaped rooms, A-frame buildings, etc.The illumination generally consists of three parts: direct sky illumination, illumination from external reflectors, and illumination from internal reflectors. First, the luminances emanating from surrounding obstructions are determined. Next, illumination traveling through the windows directly to inside walls and working surface is calculated. Finally, interreflection inside the room is taken into account to establish the luminance distributions of inside walls. After determination of all inside and outside luminances, it is a simple matter to calculate illumination and daylight factor for the working surface.     

Isogonal moulding surfaces: A family of shapes for high node congruence in free-form structures

The design of free-form structures is governed by structural and geometric considerations, the latter ones being closely linked to the costs of fabrication. If some construction constraints have been studied extensively, the question of the repeatability of nodes in free-form structures has rarely been addressed yet. In this paper, a family of surfaces that can be optimized regarding typical geometrical constraints and that exhibit high node congruence is proposed. They correspond to particular meshes of moulding surfaces and are called isogonal moulding surfaces by the authors. The geometrical properties of these surfaces are discussed. In particular, it is shown how to derive edge offset mesh from them. It is also demonstrated that they represent all the possible meshes parallel to surfaces of revolution. Finally, the reader is introduced to some computational strategies linked to isogonal moulding surfaces.     

A pore crack model for the mechanical behaviour of porous granular rocks in the brittle deformation regime

A model is developed for predicting and simulating the mechanical behaviour and failure mode of brittle porous granular rocks loaded in compression. It is based on a fracture mechanics analysis applied to cracks emanating from the surface of cylindrical pores in two-dimensional, which is well suited to the microstructure of such rocks. It is also consistent with the usual experimental procedure used for biaxial compression tests since the numerical scheme is implemented under the assumption of imposed axial strain. The model takes into account interactions between neighbouring cracks, which grow when their stress intensity factor reaches the fracture toughness of the rock. The simulation of crack growth from cylindrical holes, associated with a failure criterion based on the coalescence of interacting cracks, allows one to calculate the critical stress at rupture and to derive theoretical stress–strain curves.The present model is then used to compare theoretical results with laboratory data obtained on four sandstones with porosity ranging between 13% and 25.5% which were deformed under conventional triaxial compression conditions at confining pressures between 0 and 35 MPa. The comparison shows that by using a small number of parameters (pore size, pore density, fracture toughness, and elastic moduli), the model is able to predict the rock behaviour during the compression tests and the stress level at rupture in a quite accurate way, when the microstructural parameters introduced are consistent with the observations.     

合成材料运动场地面层中挥发性有机化合物和二硫化碳释放量的同时测定方法

建立热脱附-气相色谱-质谱法同时测定合成材料运动场地面层中挥发性有机化合物和二硫化碳释放量的方法。采用三合一吸附管,DB-5MS UI柱作为色谱柱,对热脱附解吸条件,程序升温等参数进行优化。研究表明：本实验中挥发性有机化合物分离良好,间(对)二甲苯在(0.2～2.0)μg浓度范围内线性良好,其它8种物质在(0.1～1.0)μg浓度范围内线性良好,R²均大于0.99,检出限均小于0.01[mg/(m²·h)],满足GB 36246-2018标准的要求。本方法方便高效,结果准确可靠。     

High concentrations of waste anesthetic gases induce genetic damage and inflammation in physicians exposed for three years: A cross-sectional study

This cross-sectional study analyzed the impact of occupational waste anesthetic gases on genetic material, oxidative stress, and inflammation status in young physicians exposed to inhalational anesthetics at the end of their medical residency. Concentrations of waste anesthetic gases were measured in the operating rooms to assess anesthetic pollution. The exposed group comprised individuals occupationally exposed to inhalational anesthetics, while the control group comprised individuals without anesthetic exposure. We quantified DNA damage; genetic instability (micronucleus-MN); protein, lipid, and DNA oxidation; antioxidant activities; and proinflammatory cytokine levels. Trace concentrations of anesthetics (isoflurane: 5.3 ± 2.5 ppm, sevoflurane: 9.7 ± 5.9 ppm, and nitrous oxide: 180 ± 150 ppm) were above international recommended thresholds. Basal DNA damage and IL-17A were significantly higher in the exposed group [27 ± 20 a.u. and 20.7(19.1;31.8) pg/mL, respectively] compared to the control group [17 ± 11 a.u. and 19.0(18.9;19.5) pg/mL, respectively], and MN frequency was slightly increased in the exposed physicians (2.3-fold). No significant difference was observed regarding oxidative stress biomarkers. The findings highlight the genetic and inflammatory risks in young physicians exposed to inhalational agents in operating rooms lacking adequate scavenging systems. This potential health hazard can accompany these subjects throughout their professional lives and reinforces the need to reduce ambient air pollution and consequently, occupational exposure.