Artesian conditions in the Chilterns Chalk aquifer (North West of the London Basin) and the implications for surface water - groundwater interactions

The Chalk is a principal aquifer which provides an important resource in Southeast England. For two centuries, it allowed the establishment of a thriving watercress-growing industry, indirectly through diverted stream flow and directly, through the drilling of flowing artesian boreholes. The distribution of artesian boreholes across different catchments, suggests a regional control on vertical groundwater flow within the New Pit and Lewes Chalk units. Interrogation of location-specific information points to the confining role of a few key marls within the New Pit Chalk Formation, which can be traced up-catchment to where they naturally outcrop or have been exposed by quarrying. Evidence is found in geophysical logging of a number of boreholes across catchments, confirming a consistent pattern of the spatial distribution of such key markers. When tectonic stress was applied to the various Chalk Formations, the marl bands would have reacted producing more plastic deformation and less fractures in comparison with rigid rock strata. Such scenario would have created the conditions for secondary aquifer units, giving the Chalk confining or semi-confining hydraulic characteristics on a regional scale. This conceptual understanding helps explain the reasons that the river flow response to reductions in groundwater abstraction varies across the flow duration curve.

Development model of rock relief on thick horizontal and gently sloping rock strata exposed to rain

Due to various factors influencing diverse rocks, karst phenomena take unique shapes that are most often reflected in the rock relief. Through a series of different developmental factors, new factors first gradually transform the traces of old formations and over time, if they are distinct enough, they can replace them with completely new ones. In places old forms are reflected in the formation of a new rock relief only indirectly. The rock relief of karst phenomena, in this case karren, also develops under the influence of a single factor. Developmentally, rock forms, due to dissection of the surface and lasting of development, often in several layers merge into one another. A development model enables us to discover the overall development of the formation of the selected part of the rocky karst surface. The individual rock forms which have merged into the rock relief represent just one stage of development. Good knowledge of the overall development enables us to discern the development so far and predict future development. A number of development models can be discerned. One of the basic models reveals the manner of the rain-induced formation and development of horizontal and gently sloping carbonate rock strata into karren and stone forests, especially after the disintegration of the upper (thinner) rock strata and the denudation and shaping of the bottom strata. It reveals many characteristics of rock formation, from the sheet flow to the formation of rain flutes, their merging into rain channels and the development of funnel-like notches; that is, developmental transition of rock forms and rock relief in the overall development from the flat surface to its dissection into peaks.

Particle Flow Analysis of Mechanical Properties and Failure Behaviour in Composite Rock Strata with Holes

Understanding the deformation failure behavior of the composite rock strata has important implications for deep underground engineering construction. Based on the uniaxial compression laboratory test of the specimens of composite rock strata containing holes, the microscopic parameters in the particle discrete element simulation are firstly calibrated. Then, the mechanical properties and failure characteristics of the composite rock strata with holes under different confining pressures are studied. The results show that different dip angles and confining pressures have significant effects on the peak strength and elastic modulus of the specimens. Under the same confining pressure, the peak strength and elastic modulus decrease first and then increase with the increasing dip angle. As the dip angle is constant, both the peak strength and elastic modulus gradually increase with the increase in confining pressure. It shows that the first area to be damaged in composite rock strata transfers from soft rock to hard rock with the increase in dip angle. With the increase in confining pressure, the range of tensile stress concentration area decreases substantially, while the range of compressive stress concentration area changes less.

Post-fire composition of lipids in waters and plants of Great Vasyugan Mire

A lipid compositions were determined in water and plant samples taken in natural and burnt-out areas of the Bakchar bog (northeastern part of Great Vasyugan Mire) located in the basin of the Gavrilovka River within Tomsk region and were analyzed via gas chromatography-mass spectrometry. The following main groups of organic compounds have been identified: acyclic n-alkanes, fatty acids, and n-alkan-2-ones. Among cyclic compounds steroids, sesquiterpenoids, and pentacyclic triterpenoids have been identified. It was shown that lipids in waters contained biomolecules of plants grown in the areas under study. Chemical indicators reflecting the disappearance of plants since a fire and their restricted distribution or replacement of some plant species with others were found out. These indicators can be used in paleoclimatic reconstructions to fix post-pyrogenic layers in the sedimentary rock strata.

The Vibration Characteristics of Ground of Rock Blasting in Silt-Rock Strata

As the shield section passes through the silt-rock strata, the rock stratum of the tunnel section has to be blasted into blocks in advance, and the diameter of the blocks should be less than 30 cm after breaking, and then, the blocks could smoothly enter the soil cabin through the opening of the tunnel boring machine (TBM) cutter head and finally be discharged through the screw machine. The geology of rock blasting in silt-rock strata is complex, and the vibrations caused by blasting threaten the safety of buildings around the blasting area. According to the measured data of blasting vibrations at the sites, the waveform duration of vibration acceleration and the distribution characteristics of dominant frequency of vibration velocity were analyzed, the energy characteristics of vibration velocity were researched by wavelet analysis, and the attenuation laws of vibration velocity were studied by dimensional analysis (DA). The dominant frequency bands of vibration energy of ground are in the range of 0–15.625 Hz, and the distribution characteristics of frequency bands of vibration energy in different directions of the ground are similar to each other, but the energy magnitude is different from each other. The research results could provide a reference for the safe blasting distance of buildings under similar geological conditions.

Modelling igneous rock mechanics parameter based on logging data in Shunbei oil field

In order to improve the rate of penetration (ROP) in Permian igneous rock strata, the rock mechanics is modeled based on the continuous logging data (acoustic, density, caliper, resistivity and gamma logging) and confirmatory indoor experiments. The model considers the influence of well collapse and expansion on logging data in igneous rock formation to improve the calculation accuracy. Based on this model, the continuous profile of Permian compressive strength, tensile strength, mud content, internal friction angle are calculated, and then the differences of Permian strata in the north, middle and south of the oilfield are further compared and analyzed. The results can provide support for the optimization of efficient rock breaking and reservoir fracturing technology.