Settlement Analysis of Saturated Tailings Dam Treated by CFG Pile Composite Foundation

Cement fly ash gravel (CFG) pile composite foundation is an effective and economic foundation treatment approach, which is significant to building foundation, subgrade construction, and so forth. The present paper aims at investigating the settlement behaviors of saturated tailings dam soft ground under CFG pile composite foundation treatment, in which FEM and laboratory model test were utilized. The proposed findings demonstrate that CFG pile treatment is effective in reinforcing saturated tailings dam and loading has little influence on settlement of soil between piles. The variation of soil between piles settlement in FEM has a good agreement with the laboratory model test. Additionally, the cushion deformation modulus has a small effect on the composite foundation settlement, although the cushion thickness will generate certain influence on the settlement distribution of the composite foundation

Improving Seq2Seq Grammatical Error Correction via Decoding Interventions

The sequence-to-sequence (Seq2Seq) approach has recently been widely used in grammatical error correction (GEC) and shows promising performance. However, the Seq2Seq GEC approach still suffers from two issues. First, a Seq2Seq GEC model can only be trained on parallel data, which, in GEC task, is often noisy and limited in quantity. Second, the decoder of a Seq2Seq GEC model lacks an explicit awareness of the correctness of the token being generated. In this paper, we propose a unified decoding intervention framework that employs an external critic to assess the appropriateness of the token to be generated incrementally, and then dynamically influence the choice of the next token. We discover and investigate two types of critics: a pre-trained left-to-right language model critic and an incremental target-side grammatical error detector critic. Through extensive experiments on English and Chinese datasets, our framework consistently outperforms strong baselines and achieves results competitive with state-of-the-art methods.Comment: Accept to Findings of EMNLP 202

Stress Analysis of CFG Pile Composite Foundation in Consolidating Saturated Mine Tailings Dam

Cement fly-ash gravel (CFG) pile is a widely used ground reinforcement technique. This paper aims to address the mechanical characteristics of CFG composite foundation in consolidating saturated mine tailings (MTs) dam. The field static load tests were employed to explore the bearing capacity of the CFG composite foundation, and finite element (FE) models in three dimensions validated through comparison with experimental results were used to discuss the pile-soil stress distribution and pile-soil stress ratio of the CFG composite foundation. The results indicate that the distribution of earth pressure and pile stress is relatively homogeneous and stable over depth and load, while the development of CFG composite foundation bearing capacity is insufficient, in which the developed bearing capacity of CFG piles is less than 50% of its characteristic value. Additionally, compared with the laboratory model test results, the pile-soil stress ratio decreases with the increasing of the load in FEM results proved to better conform to the actual engineering conditions. Furthermore, the deformation modulus and thickness of cushion exert significant influence on pile-soil stress ratio and integral bearing capacity of CFG composite foundation

High dynamic range photo-detection module using on-chip dual avalanche photodiodes

In this work, a high dynamic range APD-based photo-detection module is designed and developed. In the design, on-chip dual avalanche photodiodes (APDs) are fabricated with one biased to work in linear mode and the other one biased to work in single photon mode. The APD operating in linear mode is connected to a two-stage amplifier I-V conversion circuit and the APD operating in single photon mode is connected to a custom designed active quench and reset integrated circuit. The design enables the two on-chip APDs operate in different modes simultaneously without user intervention. This simplifies the system operation and a wide range of incident light intensities can be easily detected. Experimental results show that a high dynamic range of 164.2 dB is achieved by the module

Design and analysis of a photon counting system using covered single photon avalanche photodiode

A photon counting system using covered single photon avalanche diode (SPAD) based on a standard IC process (0.18 μm) is designed and analysed in this work. The SPAD is formed using the medium voltage (MV) doping layers of the process. To reduce the dark count rate (DCR) in the SPAD, a shaded SPAD with the same structure is fabricated on the same chip which is covered by a metal layer and only providing DCR for the DCR correction. This DCR provided by the shaded SPAD can be also used for the real-time on chip monitoring of some other parameters such as temperature, breakdown voltage and afterpulsing probability. Experimental results show that the SPAD developed is able to detect the visible light from 450 nm to 850 nm with a 35 % peak photon detection probability achieved at around 550 nm with bias voltage of 16 V (excess voltage of 3 V). A timing jitter of 176 ps is measured with an excess voltage of 3 V. The dark count rate in the SPAD tested is about 1.38 cps/μm2 with excess bias voltage of 1 V and 14.62 cps/μm2 with the excess bias voltage of 3 V without the DCR correction. Results also show that a reduction of more than 85 % in the DCR (background noise) can be achieved when the DCR correction is applied resulting in a DCR of 1.68 cps/μm2 with excess bias voltage of 3 V. By monitoring the DCR of the shaded SPAD, the breakdown voltage and temperature of other on chip SPAD can be measured. The potential usefulness of the afterpulsing probability monitoring using the shaded SPAD and the crosstalk probability between SPADs on the chip are analyzed. In addition, the effects of process variations on the SPAD performance is investigated by testing 10 chips with the same SPADs fabricated and potential method is proposed for alleviating the process variations in the SPAD arrays

On-Chip Photon Angular Momentum Absolute Measurement Based on Angle Detection

Photon angular momentum (AM) has been widely studied due to its unique properties. The accurate detection of photon AM is very important in its wide applications. Though various on-chip AM detectors based on surface plasmon polaritons (SPPs) have been proposed, most of them can only realize relative measurement. For example, most photon orbital angular momentum (OAM) detectors measure the high order OAM via measuring the relative interval between the intensity spots of the SPPs excited by the target order OAM beam and the reference order (usually 0th order) OAM beam. In this paper, we propose a simple on-chip photon AM detector. It can realize absolute measurement of photon OAM via angle detection, whose measurement result does not depend on the measurement of any reference OAM beam. At the same time, it can also recognize photon spin angular momentum (SAM). The proposed detector provides a new way for absolute measurement of photon AM, which may have some potential applications in the field of integrated photonic device

A Comparative Study of Protective Schemes for Shield Tunneling Adjacent to Pile Groups

Shield tunneling adjacent to pile groups is always an unavoidable problem in urban metro construction. A case was found in the project of Tianjin Metro Line 7, where a shield tunnel would be constructed near the existing pile groups of Shiyou Bridge. The whole shield tunnel is close to pile groups, and the minimum distance is only 0.8 m. Therefore, four kinds of protective schemes are proposed in this paper. It is vital to select an appropriate protective scheme to guarantee the safety during the tunnel construction. In this study, the main mechanical characteristic and physical parameters of site soil were obtained through laboratory tests. Besides, the three-dimensional finite element method was carried out to compare and analyze the effectiveness of the protective schemes in mitigating the effects of tunneling on adjacent pile groups. The results show that the deep-hole grouting scheme has better control effect on the lateral deformation and bending moment of piles, while the pile foundation underpinning scheme has better effectiveness on reducing the settlement of bridge structure and ground deformation. Finally, the deep-hole grouting reinforcement scheme will be adopted to ensure the shield passing through the pile groups smoothly

Displacement and Stress Characteristics of Tunnel Foundation in Collapsible Loess Ground Reinforced by Jet Grouting Columns

Collapsible loess tunnel foundation reinforcement is a new challenge in the construction process of tunnel engineering. According to the field displacement and stress monitoring of the Fujiayao loess tunnel, this paper investigates the reinforcing effect of a high-pressure jet grouting pile on a collapsible loess tunnel foundation in the deep large-span tunnel. The field monitoring method was employed to address the performance of tunnel foundation settlement, additional stress, earth pressure, rock pressure, etc. The results indicate that the stress on the pile tops and the earth pressure between piles increase gradually over time in two stages: stress increases rapidly in the first 45 days and, after this period, stress tends to gradually stabilize. Further, stress increases uniformly with the distance from the centerline of the tunnel, and the rock pressure of the tunnel sidewalls tends to be stable within two months of being constructed. Additional stress on the tunnel foundation increases linearly with time, and it is uniformly distributed in the vertical and horizontal directions of the tunnel section. Settlement of the tunnel foundation also gradually increases with time, and it tends to be stable at 50 days from the time of construction. Additionally, the settlements of different monitoring points are similar at the same depth. The research results will further improve the theoretical knowledge of tunnel bottom reinforcement in the loess tunnel, which not only can effectively guide the design and construction of the loess tunnel and reduce disease treatment cost but also can provide the necessary basic research data and scientific theoretical basis for revision of the corresponding specifications of highway tunnels and railway tunnels

Controlling the Abrupt Autofocusing of Circular Airy Vortex Beam via Uniaxial Crystal

The propagation of many kinds of structured light beams in uniaxial crystal has been investigated. However, the investigation of the evolution of these structured light beams after the uniaxial crystal is lacking. In this paper, an evolution formula of a light beam after passing through a uniaxial crystal is derived. Based on the formula, controlling the autofocusing of a circular Airy vortex beam (CAVB) via a uniaxial crystal is studied. It is found that a uniaxial crystal can prolong the focal length of the autofocusing. By changing the crystal length, the relative weight of the left- and right-hand circular polarization components and the relative value between the orbital and spin angular momentum densities of the beam’s focal plane can be adjusted flexibly. In addition, other optical elements can be inserted between the crystal and the focus to further adjust the focal plane field distribution. The influences of inserting x- and y-polarization polarizers on the intensity distribution are calculated as examples