地源热泵的分类及其若干问题的看法

针对地源热泵的分类和名称不很统一的现状，提出了按低温热源的来源统一分类的看法，并据此对目前常用的各种土壤源、水源热泵进一步分类；并提出目前把水环热泵当作水源热泵是不合适的，应该作为空气源热泵的一种。     

葡萄牙Panasqueira钨矿地压活动分析与治理

介绍了葡萄牙Panasque ira钨矿房柱法采场地压现状,分析了空场中顶板和矿柱冒落破坏的原因,提出该矿采取防范地压的措施:对面积较大的采场,可在采场中预留宽度为11 m的隔离矿柱,以阻隔已采完但未冒落的空场,并尽可能使隔离矿柱与大断层平行,同时采取人工强制放顶与减小爆破药量等辅助措施,从而降低大面积冒落的危害。     

Effects of multiple ground layers on thermal response test analysis and ground-source heat pump simulation

A modified three-dimensional finite difference model for the borehole ground heat exchangers of a ground-source heat pump (GSHP) system was developed which accounted for multiple ground layers with different thermal properties in the borefield at no groundwater flow. The present model was used to investigate the impact of ignoring ground layers in the thermal response test (TRT) analysis and the subsequent system simulation. It was found that the adoption of an effective ground thermal conductivity and an effective ground volumetric heat capacity for a multi-layer ground determined from a TRT analysis led to very little error in the simulated long term system performance under various ground compositions investigated. The maximum difference occurred for a 3 × 3 borefield in a dual-layer ground which measured 0.5 °C or 3.9% in the rise of the borefield fluid leaving temperature with a cooling-dominated loading profile for 10 years. With the same borefield and ground composition, a dynamic simulation of the complete GSHP system was performed using the TRNSYS simulation software. It was found that the overall system performance based on the present and the old models differed very little. It was concluded that the assumption of a homogeneous ground in a TRT analysis and subsequent system simulation was appropriate and impact of ignoring ground layers was small. A single-ground-layer model, including the analytical models, was sufficient even for a multi-layer ground. This could reduce the computation time significantly, especially when simulating a large borefield.     

Heat transfer analysis of boreholes in vertical ground heat exchangers

A ground heat exchanger (GHE) is devised for extraction or injection of thermal energy from/into the ground. Bearing strong impact on GHE performance, the borehole thermal resistance is defined by the thermal properties of the construction materials and the arrangement of flow channels of the GHEs. Taking the fluid axial convective heat transfer and thermal “short-circuiting” among U-tube legs into account, a new quasi-three-dimensional model for vertical GHEs is established in this paper, which provides a better understanding of the heat transfer processes in the GHEs. Analytical solutions of the fluid temperature profiles along the borehole depth have been obtained. On this basis analytical expressions of the borehole resistance have been derived for different configurations of single and double U-tube boreholes. Then, different borehole configurations and flow circuit arrangements are assessed in regard to their borehole resistance. Calculations show that the double U-tubes boreholes are superior to those of the single U-tube with reduction in borehole resistance of 30-90%. And double U-tubes in parallel demonstrate better performance than those in series.     

Preloading using fill surcharge and prefabricated vertical drains for an airport

This paper presents the field measurements and analysis of a preloading project with the installation of prefabricated vertical drains (PVDs) in Wenzhou, China. At the site, PVDs were installed to a depth of 22?m from the ground surface with a spacing of 1.5?m in a triangular pattern. The preloading fill thickness was 6?m with a unit weight of approximately 18 kN/m³. After a total elapsed time of 310 days, approximately 3?m thick fill was removed. The measured preloading settlement was approximately 1.5?m. The measurements and analytical results indicated that the soil layer with PVD improvement reached almost 100% primary consolidation when part of the fill was removed. After partial unloading, the PVD-improved zone was in an over-consolidated state. After the runway was opened for traffic, a settlement increment of approximately 7?mm was monitored over a period of 11 months. Analysis indicated that the settlement was mainly due to the consolidation of soil layers below the PVD-improved zone and post-surcharge secondary consolidation of the PVD-improved zone. The values of the parameters related to PVD improvement were back-estimated from the field measurements. These findings can be used to guide the design of PVDs improvement along the east coast of China.     

Predicting the principal strong ground motion parameters: A deep learning approach

In this research, new models are developed to estimate the three principal time-domain parameters of seismic ground motion. A novel deep learning (DL) approach coupled with artificial neural network (ANN), namely deep neural network (DNN) is employed for predicting the strong ground motion parameters such as peak ground acceleration (PGA), peak ground velocity (PGV) and peak ground displacement (PGD). This robust technique that has extended the applications of conventional neural networks improves learning of complicated and nonlinear features via increasing the number of layers as well as the neurons in each layer. The proposed models are constructed upon the NGA-West2 database provided by PEER (Pacific Earthquake Engineering Research Center). This database is more comprehensive than NGA-West1 which was mainly considered for developing previous artificial intelligence-based prediction models. Therefore, the new models are more reliable and can be used for wider ranges of predictors. The DNN attenuation models yield accurate estimates of the site PGA, PGV and PGD based on earthquake magnitude, rake angle, source to site distance and soil shear wave velocity. In addition, it is shown that the developed models, with correlation coefficients of 0.902, 0.899 and 0.911 (for PGA, PGV and PGD respectively), outperform the existing soft computing models. Furthermore, the average values of error measures such as MAE, MAPE and RMSE for PGA, PGV and PGD equal to 0.456, 0.758 and 0.581 compare favorably with those of previous models.     

Ground penetrating radar response from voids: A demonstration using a simple model

A simple Ricker wavelet model can be used to illustrate some fundamental properties of the ground penetrating radar (GPR) response from both air- and water-filled voids. Reflections from the top and the bottom of a void overlap significantly, and generate one common characteristic of a void response: a “bright spot”, analogous to the “bright spot” observed in seismic exploration. For time delays equal to about half the pulsewidth, the reflected wavelets superimpose to yield maximum reflection amplitudes. The top reflected wavelet becomes completely separated from the bottom reflected wavelet when the void time delay exceeds twice the wavelet pulsewidth. The two wavelet reflections can be individually identified at earlier time delays, approximately equal to the wavelet pulsewidth. This is still substantial and explains why it is difficult to use GPR to infer void thicknesses, especially for air-filled voids.     

Determination of concrete rebars characteristics by enhanced post-processing of GPR scan raw data

A method for the estimation of rebar radius by post-processing the raw data acquired by the ground penetrating radar as a B-scan radargram is proposed. Considering the hyperbola trace and the diffracted amplitudes an inverse problem consisting of two steps was stated. Using at first hyperbola fitting, the wave velocity and the coordinates of the hyperbola apex are identified. Then the rebar radius is retrieved as solution of a further optimization problem for which the cost function measures the misfit between the actual value of the maximum diffracted amplitudes and their theoretical predictions. The procedure was implemented in Matlab and tested in realistic situations. The obtained results showed improved accuracy.     

参考中子辐射与辐射防护中子测量装置校准

国际标准化组织核能标准化委员会辐射防护分委员会(ISO／TC 85／SC2)最近编制了几个有关辐射防护中子测量装置校准的标准，其中ISO8529规定了参考中子辐射的特性和产生方法、辐射场校准以及场所和个人中子剂量仪(计)校准和响应的确定；此外，ISO12789—2002规定了利用模拟中子辐射场对辐射防护中子测量装置的校准。本文介绍ISO8529系列标准的主要内容及一些相关问题。     

湖南省环境天然贯穿辐射水平调查研究

本文报道了湖南省环境天然贯穿辐射水平调查的方法和结果。全省以25×25km 网格均匀布点,共布设网格点309个,各类加密点1007个。调查结果表明:(1)湖南省原野γ辐射剂量率按测点、人口和面积的加权均值分别为7.11、6.90和7.07×10~(-8)Gy·h~(-1);(2)道路γ辐射剂量率按测点平均值为7.05×10~(-8)Gy·h~(-1);(3)室内γ辐射剂量率按测点和人口加权均值分别为10.43和10.56×10~(-8)Gy·h~(-1);(4)宇宙射线电离成分所致空气吸收剂量率按测点和人口加权均值,室内分别为2.67和2.66×10~(-8)Gy·h~(-1);室外分别为3.00和2.98×10~(-8)Gy·h~(-1);(5)天然贯穿辐射(不包括中子成分)剂量率按测点和人口加权均值,室内分别为13.1和13.2×10~(-8)Gy·h~(-1),室外分别为10.1和9.88×10~(-8)Gy·h~(-1);(6)天然γ辐射、宇宙射线和天然贯穿辐射所致湖南省人均年有效剂量当量分别为0.58、0.24和0.82mSv,所致集体年有效剂量当量分别为3.1、1.3和4.4×10~4人·Sv。