To research the reinforcement effect of a rock slope with group anchorage cables and the stress characteristics of pre-stressed anchorage cables in the fractured surface, the rock slope calculated model of a wedge blo...To research the reinforcement effect of a rock slope with group anchorage cables and the stress characteristics of pre-stressed anchorage cables in the fractured surface, the rock slope calculated model of a wedge block within the double-slide face was established by using the finite difference software according to the actual slope project combined with indoor model test. The pre-stress loss rule of the anchorage cable and the distribution of axial force and the force-transferring mechanism of the anchorage cable were analyzed during simulation. Also, based on the displacement contour and the safety factor of the calculated results, the quantitative analysis for the reinforcement ef- fect of the rock slope with group pre-stressed anchorage cable was discovered. The results computed by the software conform with the data in the experiment, which can prove the effectiveness and correctness of parameter selection and model building. Keywords group anchorage reinforcement, rock slope, joint fissure, pre-stressed anchorage cable, stress characteristics展开更多
While Colleague English Tests (CET) have promoted the college English teaching, they have also led to the extension of test-oriented education and hindered students' capability in communication. To examine the val...While Colleague English Tests (CET) have promoted the college English teaching, they have also led to the extension of test-oriented education and hindered students' capability in communication. To examine the validity of CET Band Four, resumed tests were carried out in sampled students of Grade 2001 one year after they took CET-4 in December, 2002. The control class was examined with the original paper of CET-4 2002, while the treatment class was tested with the same paper in which the multiple-choice questions were all changed into the subjective ones. The test scores were processed by statistical analysis. The results showed that although there was no significant difference between the two classes in CET-4 scores, there was significant difference between them in their experimental test scores. The scores of the treatment class were significantly lower than that of the control class, which proves that CET cannot objectively reflect students' capability in communication, and thus its validity is low. To eliminate the negative backwash effect of CET, suggestions are put forward that CET be devised as a criterion-referenced test, frequency of the test be reduced, subjective questions be increased, and commercialization of the test be avoided.展开更多
While modem prestressed techniques have improved the torsion properties of high-strength concrete （HSC） composite beams with prestressed steel （PS） boxes, no research has been reported in either the national or in...While modem prestressed techniques have improved the torsion properties of high-strength concrete （HSC） composite beams with prestressed steel （PS） boxes, no research has been reported in either the national or international literature on the an- ti-torque and composite torque properties of this type of beam. With the aim of understanding the torque properties of these beams, this paper presents results of ten comprehensive tests; three of these were based on stirrup spacings and prestressing levels as the main parameters, while the other seven were based on torsional rates. The torsion tests were conducted on the re- sults which established several key parameters, including curves of constant torsion, strain curves of steel torsion, strain distri- bution of steel beams and concrete, curves of bending-moment and mid-span deflection, as well as cross strain distribution.The prestressing impact-factor method was adopted to deduce semiempirical equations for cracking torque in such composite beams. Furthermore, this involves the use of the equation of ultimate torque based on tress-model-theory of the distortion an- gle, the calculated results show good agreement with the measured values. In summary, this paper offers theoretical analysis for future applications of HSC composite beams with PS boxes, and provides both validation of the methods employed and a reference point for on-going research on composite beams and related anti-torque studies.展开更多
基金Supported by the National Natural Science Foundation of China(50874085)
文摘To research the reinforcement effect of a rock slope with group anchorage cables and the stress characteristics of pre-stressed anchorage cables in the fractured surface, the rock slope calculated model of a wedge block within the double-slide face was established by using the finite difference software according to the actual slope project combined with indoor model test. The pre-stress loss rule of the anchorage cable and the distribution of axial force and the force-transferring mechanism of the anchorage cable were analyzed during simulation. Also, based on the displacement contour and the safety factor of the calculated results, the quantitative analysis for the reinforcement ef- fect of the rock slope with group pre-stressed anchorage cable was discovered. The results computed by the software conform with the data in the experiment, which can prove the effectiveness and correctness of parameter selection and model building. Keywords group anchorage reinforcement, rock slope, joint fissure, pre-stressed anchorage cable, stress characteristics
基金This article is a product of the research programsponsored by Beijing Education Committee .
文摘While Colleague English Tests (CET) have promoted the college English teaching, they have also led to the extension of test-oriented education and hindered students' capability in communication. To examine the validity of CET Band Four, resumed tests were carried out in sampled students of Grade 2001 one year after they took CET-4 in December, 2002. The control class was examined with the original paper of CET-4 2002, while the treatment class was tested with the same paper in which the multiple-choice questions were all changed into the subjective ones. The test scores were processed by statistical analysis. The results showed that although there was no significant difference between the two classes in CET-4 scores, there was significant difference between them in their experimental test scores. The scores of the treatment class were significantly lower than that of the control class, which proves that CET cannot objectively reflect students' capability in communication, and thus its validity is low. To eliminate the negative backwash effect of CET, suggestions are put forward that CET be devised as a criterion-referenced test, frequency of the test be reduced, subjective questions be increased, and commercialization of the test be avoided.
基金supported by the National Natural Science Foundation of China (Grant No. 50879048)"948" Project of the Ministry of Water Resources of China (Grant No. 201127)
文摘While modem prestressed techniques have improved the torsion properties of high-strength concrete （HSC） composite beams with prestressed steel （PS） boxes, no research has been reported in either the national or international literature on the an- ti-torque and composite torque properties of this type of beam. With the aim of understanding the torque properties of these beams, this paper presents results of ten comprehensive tests; three of these were based on stirrup spacings and prestressing levels as the main parameters, while the other seven were based on torsional rates. The torsion tests were conducted on the re- sults which established several key parameters, including curves of constant torsion, strain curves of steel torsion, strain distri- bution of steel beams and concrete, curves of bending-moment and mid-span deflection, as well as cross strain distribution.The prestressing impact-factor method was adopted to deduce semiempirical equations for cracking torque in such composite beams. Furthermore, this involves the use of the equation of ultimate torque based on tress-model-theory of the distortion an- gle, the calculated results show good agreement with the measured values. In summary, this paper offers theoretical analysis for future applications of HSC composite beams with PS boxes, and provides both validation of the methods employed and a reference point for on-going research on composite beams and related anti-torque studies.
