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The construction of modern city consists of many underground facilities, and one major concern is how to construct them safely and efficiently. Thus, the excavation-induced pile response needs to be evaluated. Dual-row batter pile wall (DRBPW) exhibits better performance than traditional dual-row vertical pile wall (DRVPW) in foundation pit engineering. However, the study of single pile subjected to excavation-induced soil movement behind DRVPW is rather limited, needless to say that of the DRBPW. An explicit finite difference method (FDM) was utilized to obtain the responses of isolated floating single pile (IFSP) near deep excavations braced by DRBPW. The responses of IFSP in the vicinity of foundation pit reinforced by DRBPW were compared to that of the DRVPW. The pile length, distance of pile from wall, excavation depth, working load, and Young's modulus of pile were considered in the parametric study. The conclusions were as follows: (1) The DRBPW can minimize the influence on the existing pile; thus, the induced lateral displacement and bending moment of pile retained by DRBPW are smaller than that of DRVPW. (2) The excavation depth, pile location, and pile length have significant influence on the responses of IFSP adjacent excavation, while the working load and Young's modulus of pile have diminutive influence. (3) The influence zone induced by excavation can be divided into two areas. The primary influence zone is the severely affected area where the induced deformation and bending moment are remarkable. The secondary influence zone is the moderately affected area where the induced deformation and bending moment are mild. The primary influence zone is within twice of the excavation depth. The secondary influence zone is 2.0–3.0 times that of the excavation depth. (4) The pile toe of IFSP has considerable lateral displacement during excavation, and attentions should be paid to the whole pile shaft during construction. [ABSTRACT FROM AUTHOR]

To evaluate the performance of dual-row batter pile wall (DRBPW) in deep excavations, a three-dimensional numerical model was established. The plastic hardening (PH) constitutive model in FLAC3D was adopted, considering the hardening property of the soil. A series of parametric study was conducted to investigate the effect of different factors. By analyzing the maximum lateral displacement, the pile shaft deflection and bending moment of both the leading and trailing row, the effect of inclination angle, pile diameter, penetration depth, and row spacing on the behavior of DRBPW was determined. The following conclusions could be drawn: (1) The bearing capacity of DRBPW is quite larger than that of the dual-row vertical pile wall (DRVPW). With the increase of inclination angle, a substantial reduction of lateral displacement could be observed. However, the beneficial role of batter pile is almost negligible when the inclination angle is not larger than 5°. The recommended inclination degree of the batter pile is 10° to 15°. (2) The maximum displacement of the leading and trailing rows lies at a distance below the pile cap, while the maximum bending moment is located at a small distance below the dredging line. The maximum bending moment of the leading pile is approximately twice that of the trailing one, thereby indicating that the leading pile bear more lateral earth pressure than the trailing pile. (3) The pile diameter, penetration depth and row spacing should be maintained in a suitable range; otherwise, the DRBPW may fail earlier than expected. The slender ratios is recommend to be set not larger than 30. The penetration ratio should not be less than 0.22. The optimal row spacing for the DRBPW is four times the diameter. [ABSTRACT FROM AUTHOR]

Anaerobic digestion (AD) is an effective way to utilize the abundant resource of corn stover (CS). In this light, Ca(OH)2pretreatment alone, steam explosion (SE) pretreatment alone, and co-pretreatment of Ca(OH)2and SE were applied to improve the digestion efficiency of CS. Results showed that AD of co-pretreated CS with 1.0% Ca(OH)2and SE at 1.5 MPa achieved the highest cumulative methane yield of, which was 61.54% significantly higher (p < .01) than untreated CS. The biodegradability value of CS after co-pretreatment enhanced from 43.03% to 69.52%. Methane yield could be well fitted by the first-order model and the modified Gompertz model. In addition, composition and structural changes of CS after pretreatment were analyzed by a fiber analyzer, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. The validated results indicated that co-pretreatment of Ca(OH)2and SE was efficient to improve the digestion performance of CS and might be a suitable method for agricultural waste pretreatment in the future AD industry. [ABSTRACT FROM PUBLISHER]

In this study, three batch tests were conducted to investigate the effect of total solids loading, substrate to inoculum ratio, and fermentation temperatures on mixed-acids (total volatile fatty acids, TVFA) production from food waste (FW). Results showed that adding anaerobic inoculum could largely increase the extent of acidification of FW. Temperature could significantly influence the mixed-acids yield. Increasing S/I (substrate to inoculum ratio (on volatile solid basis)) ratio from 3 to 9 resulted in lower TVFA yields. The highest TVFA production with a concentration of 18.4 g/L (as acetic acid) was found at 6.0% TS (total solid) loading, 3 S/I ratio, and 37°C. [ABSTRACT FROM AUTHOR]

Water-soluble monomer APEG-PG-(OH)n were produced and the Structure of APEG-PG-(OH)5 were identified by 1H-NMR. APEG-PG-(OH)n were copolymerized with maleic anhydride (MA) to synthesize no phosphate and nitrogen free calcium carbonate inhibitor MA/APEG-PG-(OH)n. The structure and thermal property of MA/APEG-PG-(OH)5 were characterized and measured by 1H-NMR, GPC and TGA. The observation shows that the dosage and n value of MA/APEG-PG-(OH)n plays an important role on CaCO3 inhibition. MA/APEG-PG-(OH)5 displays superior ability to inhibit the precipitation of calcium carbonate, with approximately 97% inhibition at a level of 8 mg/L. The effect on formation of CaCO3 was investigated with combination of SEM and XRD analysis. [ABSTRACT FROM AUTHOR]

Formation of mineral scales of carbonate and sulphate poses significant problems in cooling water systems. For the control of calcium carbonate and calcium sulphate scales, a novel environmentally friendly type of scale inhibitor ALn was synthesized. The antiscale property of the ALn copolymer towards CaCO3and CaSO4in the artificial cooling water was studied through static scale inhibition tests, The observation shows that both CaCO3and CaSO4inhibition increase with increasing the degree of polymerization of ALn from 5 to 15, andthe dosage of ALn plays an important role on CaCO3and CaSO4inhibition. The effect on formation of CaCO3and CaSO4was investigated with combination of scanning electronic microscopy, transmission electron microscopy, and X-ray powder diffraction analysis, respectively. Inhibition mechanism is proposed that the interactions between calcium and polyethylene glycol are the fundamental impetus to restrain the formation of the scale in cooling water systems. [ABSTRACT FROM AUTHOR]

Allyloxy polyethoxy ether (APEG) and succinic anhydride were used to prepare allyloxy polyethoxy carboxylate (APEL). 8-hydroxy-1,3,6-pyrene trisulfonic acid trisodium salt (PY) was reacted with allyl chloride to produce fluorescent monomer 8-allyloxy-1,3,6-pyrene trisulfonic acid trisodium salt (PA). APEL and PA were copolymerized with acrylic acid (AA) to synthesize PA tagged no phosphate and nitrogen free CaCO3inhibitor AA-APEL-PA. Structures of PA, APEG, APEL, and AA-APEL-PA were carried out by FT-IR and1H-NMR. The observation shows thatthe dosage of AA-APEL-PA plays an important role on CaCO3inhibition. The effect on formation of CaCO3was investigated with combination of scanning electronic microscopy and X-ray powder diffraction analysis. Relationship between AA-APEL-PA's fluorescent intensity and its dosage was studied. Correlation coefficient r of AA-APEL-PA's fluorescent intensity and its dosage is 0.9998. AA-APEL-PA can be used to accurately measure polymer consumption on line besides providing excellent CaCO3inhibition. [ABSTRACT FROM AUTHOR]

Allyloxy polyethoxy ether (APEG) and succinic anhydride were used to prepare allyloxy polyethoxy carboxylate (APEL). The 8-hydroxy-1,3,6-pyrene trisulfonic acid trisodium salt (PY) was reacted with allyl chloride to produce fluorescent monomer 8-allyloxy-1,3,6-pyrene trisulfonic acid trisodium salt (PA). APEL and PA were copolymerized with acrylic acid (AA) to synthesize PA-tagged no phosphate and nitrogen free calcium phosphate inhibitor AA–APEL–PA. Structures of PA, APEG, APEL, and AA–APEL–PA were carried out by FT-IR and1H NMR. Different AA:APEL mole ratios were employed for the manufacture of AA–APEL–PA to study the effect of mole ratio on performance of AA–APEL–PA. Relationship between AA–APEL–PA’s fluorescent intensity and its dosage was studied. The results indicate that capability of AA–APEL–PA is heavily depended on the mole ratio of AA:APEL. Correlation coefficient r of AA–APEL–PA’s fluorescent intensity and its dosage is 0.9995, and detection limit of AA–APEL–PA is 0.98 mg/L. AA–APEL–PA can be used to accurately measure polymer consumption on line besides providing excellent calcium phosphate inhibition. [ABSTRACT FROM PUBLISHER]

Carboxylate-ended poly(ethylene glycol) macromonomers, namely allylpolyethoxy carboxylate (APEC), were prepared by means of a carboxy methylation technique with the obvious advantage of energy conservation. APEC and acrylic acid (AA) were then used as monomers to obtain AA/APEC copolymers. Fourier-transform infrared spectra and nuclear magnetic resonance were employed to characterize AA/APEC structure. Observations showed that AA/APEC was a much better inhibitor both for calcium phosphate and calcium sulfate compared to the commercial inhibitors, and it was also an effective inhibitor, even at elevated temperature, pH, Ca2+ and Fe2+ concentration or in the presence of biocides. [ABSTRACT FROM AUTHOR]