Combined bodies of rock-like material and rock are widely encountered in geotechnical engineering,such as tunnels and mines.The existing theoretical models describing the stress-strain relationship of a combined body ...Combined bodies of rock-like material and rock are widely encountered in geotechnical engineering,such as tunnels and mines.The existing theoretical models describing the stress-strain relationship of a combined body lack a binary feature.Based on effective medium theory,this paper presents the governing equation of the“elastic modulus”for combined and single bodies under triaxial compressive tests.A binary effective medium model is then established.Based on the compressive experiment of concretegranite combined bodies,the feasibility of determining the stress threshold based on crack axial strain is discussed,and the model is verified.The model is further extended to coal-rock combined bodies of more diverse types,and the variation laws of the compressive mechanical parameters are then discussed.The results show that the fitting accuracy of the model with the experimental curves of the concretegranite combined bodies and various types of coal-rock combined bodies are over 95%.The crack axial strain method can replace the crack volumetric strain method,which clarifies the physical meanings of the model parameters.The variation laws of matrix parameters and crack parameters are discussed in depth and are expected to be more widely used in geotechnical engineering.展开更多
Based on the instantaneous high-pressure(IHP)produced by high-pressure single pole-cylinder pump, the effects of combining this pressure with medium temperature on the retention of total vitamin C(Vc)in wax gourd juic...Based on the instantaneous high-pressure(IHP)produced by high-pressure single pole-cylinder pump, the effects of combining this pressure with medium temperature on the retention of total vitamin C(Vc)in wax gourd juices were investigated under 20 - 80 MPa, 35 - 58℃, pH 3. 0 - 6. 0 and processing time 0-8 min. Results showed that the loss of Vc increased with elevated processing temperatures(50 MPa, 4 min). When the temperature of raw juices was 35℃, the retention of total Vc was higher under 40 - 60 MPa than that under the pressure < 40 MPa or > 60 MPa, and it was up to 94%(4 min). The retention of total Vc decreases slowly within 6 min, but rapidly after 6 min. The pH can also influence the retention of total Vc, and this retention can come to a highest point at pH 6.0.展开更多
Based on the instantaneous pressurization and depressurization produced by high pressure single pole cylinder pump and valve, the effects of the continuous processing on the peroxidase (POD) activity in wax gourd ju...Based on the instantaneous pressurization and depressurization produced by high pressure single pole cylinder pump and valve, the effects of the continuous processing on the peroxidase (POD) activity in wax gourd juices were investigated. Results showed that the processing factors such as pressure, temperature, pH and processing time are important to the POD activity. POD in crude juices could be inactivated apparently above 50 MPa(pH 4.6, 35℃, 4 min), and activated at 20 MPa ( P < 0.01). Its remarkable inactivation could also be observed at 45 and 55℃ (20 MPa, pH 4.6, 4 min), and the evident activation appears at the material temperature 35℃ ( P < 0.01). The pH 3.0 could destroy POD almost completely (20 MPa, 35℃, 4 min), while pH 6.0 could not influence apparently the POD activity in crude juices( P > 0.05). In addition, the rules of POD activity along with the treatment time are variational under different processing pressures. The higher the treating pressure is, the shorter the processing time is needed to inactivate POD.展开更多
充填体—边界介质组合体接触面的剪切力学特性与参数是研究充填采场应力分布与充填体揭露稳定性评价的基础数据。通过室内直剪试验与RFPA^(3D)数值模拟试验联合手段,对3种灰砂配比(1∶4、1∶8和1∶20)、4种接触面法向应力(50 k Pa、100 ...充填体—边界介质组合体接触面的剪切力学特性与参数是研究充填采场应力分布与充填体揭露稳定性评价的基础数据。通过室内直剪试验与RFPA^(3D)数值模拟试验联合手段,对3种灰砂配比(1∶4、1∶8和1∶20)、4种接触面法向应力(50 k Pa、100 k Pa、150 k Pa和200 k Pa)的充填体—边界介质组合体(充填体—围岩、充填体—矿体、胶结充填体—非胶结充填体)的剪切力学特性与声发射特征、黏聚力和内摩擦角参数变化规律进行了分析。结果表明:随灰砂配比降低,充填体—围岩组合体峰值剪切强度减少,破坏模式由脆性变为延性,破坏形态由颗粒粘连、块状粘连到凸起体尖端被剪断。灰砂配比1∶4组合体发生破坏时剪切应力垂直下降,振铃计数率突然骤增,其他阶段振铃计数率相对较小。灰砂配比1∶8和1∶20组合体从裂隙压密到破坏阶段,声发射振铃计数率密集,剪切过程中有明显剪胀变形;充填体—边界介质组合体接触面的峰值剪切强度随法向应力、灰砂配比降低而减少。胶结充填体—围岩接触面峰值剪切强度略小于胶结充填体—矿体强度,胶结—非胶结充填体组合体峰值强度远小于胶结充填体—矿岩组合体,接近非胶结充填体自身强度;充填体—边界介质组合体接触面的黏聚力和内摩擦角随灰砂配比降低而减少。充填体—围岩与充填体—矿体黏聚力和内摩擦角接近,胶结—非胶结充填体组合体黏聚力和内摩擦角参数远小于胶结充填体—矿岩组合体。研究结果拓展了充填体—边界介质组合体剪切力学特性获取方法,为充填采场稳定性分析提供了基础数据。展开更多
基金the Major Program of National Natural Science Foundation of China(No.41941019)Shaanxi Province Innovative Talent Promotion Plan-Science and Technology Innovation Team(No.2021TD-55)Central University Natural Science Innovation Team(No.300102262402)。
文摘Combined bodies of rock-like material and rock are widely encountered in geotechnical engineering,such as tunnels and mines.The existing theoretical models describing the stress-strain relationship of a combined body lack a binary feature.Based on effective medium theory,this paper presents the governing equation of the“elastic modulus”for combined and single bodies under triaxial compressive tests.A binary effective medium model is then established.Based on the compressive experiment of concretegranite combined bodies,the feasibility of determining the stress threshold based on crack axial strain is discussed,and the model is verified.The model is further extended to coal-rock combined bodies of more diverse types,and the variation laws of the compressive mechanical parameters are then discussed.The results show that the fitting accuracy of the model with the experimental curves of the concretegranite combined bodies and various types of coal-rock combined bodies are over 95%.The crack axial strain method can replace the crack volumetric strain method,which clarifies the physical meanings of the model parameters.The variation laws of matrix parameters and crack parameters are discussed in depth and are expected to be more widely used in geotechnical engineering.
文摘Based on the instantaneous high-pressure(IHP)produced by high-pressure single pole-cylinder pump, the effects of combining this pressure with medium temperature on the retention of total vitamin C(Vc)in wax gourd juices were investigated under 20 - 80 MPa, 35 - 58℃, pH 3. 0 - 6. 0 and processing time 0-8 min. Results showed that the loss of Vc increased with elevated processing temperatures(50 MPa, 4 min). When the temperature of raw juices was 35℃, the retention of total Vc was higher under 40 - 60 MPa than that under the pressure < 40 MPa or > 60 MPa, and it was up to 94%(4 min). The retention of total Vc decreases slowly within 6 min, but rapidly after 6 min. The pH can also influence the retention of total Vc, and this retention can come to a highest point at pH 6.0.
文摘Based on the instantaneous pressurization and depressurization produced by high pressure single pole cylinder pump and valve, the effects of the continuous processing on the peroxidase (POD) activity in wax gourd juices were investigated. Results showed that the processing factors such as pressure, temperature, pH and processing time are important to the POD activity. POD in crude juices could be inactivated apparently above 50 MPa(pH 4.6, 35℃, 4 min), and activated at 20 MPa ( P < 0.01). Its remarkable inactivation could also be observed at 45 and 55℃ (20 MPa, pH 4.6, 4 min), and the evident activation appears at the material temperature 35℃ ( P < 0.01). The pH 3.0 could destroy POD almost completely (20 MPa, 35℃, 4 min), while pH 6.0 could not influence apparently the POD activity in crude juices( P > 0.05). In addition, the rules of POD activity along with the treatment time are variational under different processing pressures. The higher the treating pressure is, the shorter the processing time is needed to inactivate POD.
文摘充填体—边界介质组合体接触面的剪切力学特性与参数是研究充填采场应力分布与充填体揭露稳定性评价的基础数据。通过室内直剪试验与RFPA^(3D)数值模拟试验联合手段,对3种灰砂配比(1∶4、1∶8和1∶20)、4种接触面法向应力(50 k Pa、100 k Pa、150 k Pa和200 k Pa)的充填体—边界介质组合体(充填体—围岩、充填体—矿体、胶结充填体—非胶结充填体)的剪切力学特性与声发射特征、黏聚力和内摩擦角参数变化规律进行了分析。结果表明:随灰砂配比降低,充填体—围岩组合体峰值剪切强度减少,破坏模式由脆性变为延性,破坏形态由颗粒粘连、块状粘连到凸起体尖端被剪断。灰砂配比1∶4组合体发生破坏时剪切应力垂直下降,振铃计数率突然骤增,其他阶段振铃计数率相对较小。灰砂配比1∶8和1∶20组合体从裂隙压密到破坏阶段,声发射振铃计数率密集,剪切过程中有明显剪胀变形;充填体—边界介质组合体接触面的峰值剪切强度随法向应力、灰砂配比降低而减少。胶结充填体—围岩接触面峰值剪切强度略小于胶结充填体—矿体强度,胶结—非胶结充填体组合体峰值强度远小于胶结充填体—矿岩组合体,接近非胶结充填体自身强度;充填体—边界介质组合体接触面的黏聚力和内摩擦角随灰砂配比降低而减少。充填体—围岩与充填体—矿体黏聚力和内摩擦角接近,胶结—非胶结充填体组合体黏聚力和内摩擦角参数远小于胶结充填体—矿岩组合体。研究结果拓展了充填体—边界介质组合体剪切力学特性获取方法,为充填采场稳定性分析提供了基础数据。
